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• Summary of TaleoWorld 2012

  - by Scott Ewart

  Taleo World resulted in lively, positive conversation on social media, with 1,595 references on Twitter. Conversation was driven by users live-tweeting about the keynotes, product sessions/demos and customers. The Wednesday morning keynote resulted in a spike, and users responded positively to executive’s view on HCM and the innovative Oracle-Taleo product roadmap.   This is a recap of the Twitter feed conversations highlighting top tweets and photos, as well as supporting materials, including the resulting coverage.  Please read The Taleo World Storify and click here. Five unique articles appeared on Taleo World. The Ventana Research blog and InformationWeek wrote in-depth articles focusing on Mark Hurd’s presentation, product strategy, and demonstrations of Oracle Taleo Cloud Service Feature Pack 12B and Oracle Fusion Tap, overall stressing Oracle’s commitment to customers and product development. To view the full-text of all articles , please click below on the articles' name. Oracle Presents a Taleo Future for Human Capital Management - Ventana Research blog Innovation as a Choice - Steve Boese's HR Technology blog Oracle Touts Taleo As HCM Heats Up - InformationWeek With 43% of the Current Workforce Retiring In 10 Years, What’s A CEO To Do? - HireVue Digital Distortion blog  What’s Your Recruitment Metrics Story? - SmashFly Recruitment Marketing Technology blog.

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• HLSL - Creating Shadows in 2D

  - by richard

  The way that I create shadows is by the following technique: http://www.catalinzima.com/2010/07/my-technique-for-the-shader-based-dynamic-2d-shadows/ But I have questions to HLSL. The way that I currently do it is, I have a black and white image, where Black means 'object', and white means 'nothing'. I then distort the image like in the tutorial. I do this with a pixel shader, but instead of rendering to the screen, I render to a texture, back to my application. I then take this, and create the shadows, and then send it back to the graphics card to undo the distortion, after the shadow has been added - this comes back and I have a stencil of shadow. I can put this ontop of the original image and send them back to the graphics card, which then puts them on the screen. To me this is alot of back and forth. Is there a way i can avoid this? The problem that I am having is that I need to basically go through all positions in the texture 3 times, and use the new new texture every time instead of the orginal one. I tried to read up on Passes, but i don't think that i am heading in the right direction there. Help?

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• Orthographic unit translation mismatch on grid (e.g. 64 pixels translates incorrectly)

  - by Justin Van Horne

  I am looking for some insight into a small problem with unit translations on a grid. Setup 512x448 window 64x64 grid gl_Position = projection * world * position; projection is defined by ortho(-w/2.0f, w/2.0f, -h/2.0f, h/2.0f); This is a textbook orthogonal projection function. world is defined by a fixed camera position at (0, 0) position is defined by the sprite's position. Problem In the screenshot below (1:1 scaling) the grid spacing is 64x64 and I am drawing the unit at (64, 64), however the unit draws roughly ~10px in the wrong position. I've tried uniform window dimensions to prevent any distortion on the pixel size, but now I am a bit lost in the proper way in providing a 1:1 pixel-to-world-unit projection. Anyhow, here are some quick images to aide in the problem. I decided to super-impose a bunch of the sprites at what the engine believes is 64x offsets. When this seemed off place, I went about and did the base case of 1 unit. Which seemed to line up as expected. The yellow shows a 1px difference in the movement. Vertices It would appear that the vertices going into the vertex shader are correct. For example, in reference to the first image the data looks like this in the VBO: x y x y ---------------------------- tl | 0.0 24.0 64.0 24.0 bl | 0.0 0.0 -> 64.0 0.0 tr | 16.0 0.0 80.0 0.0 br | 16.0 24.0 80.0 24.0 With that said, all I am left to believe is that I am munging up my actual projection. So, I am looking for any insight into maintaining the 1:1 pixel-to-world-unit projection.

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• XNA Windows Resolution / Mouse Position Bug

  - by Ian Hern

  In XNA, when in windowed mode and resolution (set via PreferredBackBufferWidth/Height) is close to the resolution of the display, the view is distorted (zoomed in a bit)and the mouse coordinates are wrong. Here is what it looks like when I draw a bunch of lines to the screen. (Normal, Error on my ASUS Notebook G73Jh, Error on my EEE PC 1001P) In the top left of the screen the mouse position is correct, but the further you get away the more out of sync it becomes. Here are some images of the mouse in different positions and the game drawing a circle underneath where it thinks the mouse is. (Top Left, Bottom Right) If you shrink the resolution by a couple pixels then it goes back to working like normal, my first though at a fix was to limit the max resolution to a little smaller than the display resolution. I figured out the maximum resolution that works in a couple different modes, but there doesn't seem to be a pattern that would allow me to determine it based off the display resolution. Computer | Screen Resolution | Max Error-Free | Difference ASUS Notebook G73Jh | 1920x1080 | 1924x1059 | +4x-21 ASUS Notebook G73Jh | 1024x600 | 1018x568 | -6x-32 EEE PC 1001P | 1024x600 | 1020x574 | -4x-26 Because the differences don't form a pattern I can't hack in a solution, the one even has +4 which baffles me. Here is a project that demonstrates the problem, just set the resolution to the resolution of your display. Any ideas on how I might fix this issue? As an insteresting aside, I tried to use FRAPS to capture a video of the issue but fraps actually records without distortion or mouse offset.

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• Is there any algorithm for finding LINES by PIXEL COLORS on picture?

  - by Ole Jak

  So I have Image like this I want to get something like this (I hevent drawn all lines I want but I hope you can get my idea) I need algorithm for finding all straight lines on it by just reading colors of pixels. No hard math, no Haar, no Hough. Some algorithm which would be based on points colors. I want to give to algorithm parameters like min line length and max line distortion. I want to get relative to picture pixel coords start and end points of lines. So I need algorithm for finding straight lines of different colors on picture. Algorithm which would be based on idea of image of different colors and Lines of static colors. Yes - such algorithm will not work for images with lots of shadows and lights. But It willl probably be fast (I hope so). Is there any such algorithm?

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• Is there any super fast algorithm for finding LINES on picture?

  - by Ole Jak

  So I have Image like this I need some super fast algorithm for finding all straight lines on it. I want to give to algorithm parameters like min length and max line distortion. I want to get relative to picture pixel coords start and end points of lines. So on this picture to find all lines between dalles and thouse 2 black lines on top. So I need algorithm for super fast finding straight lines of different colors on picture. Is there any such algorithm? (super duper fast=)

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• Spatial index for geo coordinates?

  - by Michael Borgwardt

  What kind of data structure could be used for an efficient nearest neighbor search in a large set of geo coordinates? With "regular" spatial index structures like R-Trees that assume planar coordinates, I see two problems (Are there others I have overlooked?): Wraparound at the poles and the International Date Line Distortion of distances near the poles How can these factors be allowed for? I guess the second one could compensated by transforming the coordinates. Can an R-Tree be modified to take wraparound into account? Or are there specialized geo-spatial index structures?

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• Metric 3d reconstruction

  - by srand

  I'm trying to reconstruct 3D points from 2D image correspondences. My camera is calibrated. The test images are of a checkered cube and correspondences are hand picked. Radial distortion is removed. After triangulation the construction seems to be wrong however. The X and Y values seem to be correct, but the Z values are about the same and do not differentiate along the cube. The 3D points look like as if the points were flattened along the Z-axis. What is going wrong in the Z values? Do the points need to be normalized or changed from image coordinates at any point, say before the fundamental matrix is computed? (If this is too vague I can explain my general process or elaborate on parts)

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• Automatic camera calibration

  - by srand

  From Wikipedia, camera resectioning is the process of finding the true parameters of the camera that produced a given photograph or video. Camera resectioning is also known as geometric camera calibration. Currently I am using Camera Calibration Toolbox for Matlab for my camera calibration. The toolbox returns calibration parameters such as focal length, principle point, skew, and distortion. However, the issue with this method is that it requires an extra step in calibrating the camera by using a special calibration object like a checkerboard. Additionally, it only works for one focus of the camera. How can I get the calibration parameters without manually calibrating? For example, how does Microsoft's Photosynth perform camera calibration on its images?

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• Is there a way to morph / convert a circular sprite into a square programmatically?

  - by John

  I have a sprite which is basically just an image of a circle and some content inside. Is there a way that I can programmatically stretch / distort it into something like: I don't care so much about the distortion. The original circular image is 100x100px, and the modified image should also be 100x100px. So its really the content that is being distorted. Can this be done using shaders or some other programmatic way ? The initial circular image is most likely determined at run time, which is why I need to programmatically convert the circular sprite to square. Please do not edit the tags, as the question applies to both versions of cocos2d (iPhone & x), and the solution will most likely work in both regardless of whether one uses C or C++ since the apis are similar, and OpenGL commands work similarly.

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• Matching a rotated bitmap to a collage image

  - by Dmi

  Hi, My problem is that I have an image of a detailed street map. On this map, there can be a certain small image of a sign (such as a traffic light icon) rotated at any angle, maybe resized. I have this small image in a bitmap. Is there any algorithm or technique by which I can locate this bitmap if a copy of it exists, rotated and maybe resized, in the large collage image? This is similar to the problem with Augmented Reality and locating the marker image, but mine is only 2D with no perspective distortion.

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• What size should the background image in an MSI be?

  - by r_

  I am trying to create a Windows Installer package using Wix. I'm getting a lot of conflicting information about what size my custom background should be--the Wix documentation suggests a size of 500 x 314 pixels, but this leads to slight image distortion in the installer. I believe that I may be indirectly using the SplashBitmap property in Windows Installer, whose documentation suggests 480 x 320 is the correct size. When I try to use this image size, I also get artefacts in the image. Could anyone tell me what the correct size should be?

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• Software to clean up photos of whiteboards and documents?

  - by Norman Ramsey

  I take a lot of photos of whiteboards, blackboards, and so on for teaching purposes (examples online through May 2010). I'm interested in cleaning them up for archival purposes, preferably using Linux. Commercial products ClearBoard and PhotoNote are priced a little aggressively for my purposes, plus my students would like to have this capability too. Does anyone know of any good, open source software for Converting photographs to images with just a few colors? Eliminating perspective distortion? Removing unwanted junk from around the edges of an image? or anything like that? I'm imagining that I start out with a picture of my whiteboard using red and black markers, and I end up with a three-color image using just white, red, and black. Or I photograph a laser-printed document and end up with a clean black-and-white image. I have tried standard tools that reduce the number of colors in an image, and they do a terrible job—probably because they are trying to reproduce the uneven illumination of the original image. Command-line Linux tools would be ideal.

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• Screen Flickering: Hardware or Software?

  - by Wesley

  I have a Samsung N120 netbook (upgraded to 2GB DDR2 RAM) and there has been a screen flickering issue for some time now. However, I have not been able to accurately determine whether it is a software or hardware issue. Here are some of the symptoms: The flicker is white-colored and shows up as vertical lines. Flickering or not, there may be occasionally some random blue patterns (no image distortion) The screen tends to flicker more when the screen is not tilted back all the way. When tilting the screen back and forth, the screen will usually flicker. Some images on the screen may randomly distort without full-on flickering. The screen will flicker only on certain websites, but not on others. A certain part of a webpage may constantly be distorted randomly, even when scrolling. While flickering, the mouse will not move though I'm moving my finger along the touchpad. A connected external monitor does not have any problems. The flickering is completely random and does not seem to follow any CPU/GPU usage trends. Flickering usually gets worse when the screen brightness is turned higher. There will be flickering on battery and while plugged in. Search up "Samsung N120 - Screen Flickering" on YouTube for an idea of what the flickering looks like. However, there is no visible distortions and the flickering seems to stop when the screen has dimmed. Since the problems started, I tried formatting and using Windows 7, then formatted again and went back to Windows XP. The screen was also replaced sometime during this past summer. The uninstallation of the Samsung Battery Manager (on the original install of XP) seemed to reduce the flicker partially, but eventually got worse. So, what could possibly be the problem?

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• Problems when pasting Outlook 2010 signature logo into message body

  - by Austin ''Danger'' Powers

  Whenever I paste my company logo into a message in Outlook 2010, I run into a variety of complications and anomalies. The dimensions of my original logo image are 315x174 (source image is a PNG file). I am scaling this image down in Photoshop CS6 to a variety of smaller sizes for testing my Outlook signature (300x166, 250x138, 200x110,150x83 and 100x55 pixels). 300x166 = no distortion. This looks the same as in Photoshop (but far too large to use in my signature). 250x130 = distorted (gets stretched much wider by Outlook when pasting into message body). 200x110 = looks reasonable, but seems to have been scaled to a different size (smaller) by Outlook for no obvious reason. 150x83 = for some reason, this is scaled by Outlook to the exact same size that 200x110 was scaled to. In fact, a large range of similar dimensions are scaled to the exact same image size by Outlook. This is very frustrating. Why is this happening and what can be done to prevent it? 100x55 = when pasting my logo from Photoshop to Outlook with these dimensions all that happens is the cursor jumps forwards about an inch on the screen, leaving a blank space where the image was supposed to go. Any advice would be much appreciated.

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• Managing Operational Risk of Financial Services Processes – part 2/2

  - by Sanjeev Sharma

  Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif"; mso-bidi-font-family:"Times New Roman";} In my earlier blog post, I had described the factors that lead to compliance complexity of financial services processes. In this post, I will outline the business implications of the increasing process compliance complexity and the specific role of BPM in addressing the operational risk reduction objectives of regulatory compliance. First, let’s look at the business implications of increasing complexity of process compliance for financial institutions: · Increased time and cost of compliance due to duplication of effort in conforming to regulatory requirements due to process changes driven by evolving regulatory mandates, shifting business priorities or internal/external audit requirements · Delays in audit reporting due to quality issues in reconciling non-standard process KPIs and integrity concerns arising from the need to rely on multiple data sources for a given process Next, let’s consider some approaches to managing the operational risk of business processes. Financial institutions considering reducing operational risk of their processes, generally speaking, have two choices: · Rip-and-replace existing applications with new off-the shelf applications. · Extend capabilities of existing applications by modeling their data and process interactions, with other applications or user-channels, outside of the application boundary using BPM. The benefit of the first approach is that compliance with new regulatory requirements would be embedded within the boundaries of these applications. However pre-built compliance of any packaged application or custom-built application should not be mistaken as a one-shot fix for future compliance needs. The reason is that business needs and regulatory requirements inevitably out grow end-to-end capabilities of even the most comprehensive packaged or custom-built business application. Thus, processes that originally resided within the application will eventually spill outside the application boundary. It is precisely at such hand-offs between applications or between overlaying processes where vulnerabilities arise to unknown and accidental faults that potentially result in errors and lead to partial or total failure. The gist of the above argument is that processes which reside outside application boundaries, in other words, span multiple applications constitute a latent operational risk that spans the end-to-end value chain. For instance, distortion of data flowing from an account-opening application to a credit-rating system if left un-checked renders compliance with “KYC” policies void even when the “KYC” checklist was enforced at the time of data capture by the account-opening application. Oracle Business Process Management is enabling financial institutions to lower operational risk of such process ”gaps” for Financial Services processes including “Customer On-boarding”, “Quote-to-Contract”, “Deposit/Loan Origination”, “Trade Exceptions”, “Interest Claim Tracking” etc.. If you are faced with a similar challenge and need any guidance on the same feel free to drop me a note.

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• How to perform spatial partitioning in n-dimensions?

  - by kevin42

  I'm trying to design an implementation of Vector Quantization as a c++ template class that can handle different types and dimensions of vectors (e.g. 16 dimension vectors of bytes, or 4d vectors of doubles, etc). I've been reading up on the algorithms, and I understand most of it: here and here I want to implement the Linde-Buzo-Gray (LBG) Algorithm, but I'm having difficulty figuring out the general algorithm for partitioning the clusters. I think I need to define a plane (hyperplane?) that splits the vectors in a cluster so there is an equal number on each side of the plane. [edit to add more info] This is an iterative process, but I think I start by finding the centroid of all the vectors, then use that centroid to define the splitting plane, get the centroid of each of the sides of the plane, continuing until I have the number of clusters needed for the VQ algorithm (iterating to optimize for less distortion along the way). The animation in the first link above shows it nicely. My questions are: What is an algorithm to find the plane once I have the centroid? How can I test a vector to see if it is on either side of that plane?

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• How to have screen revert to BLACK between pages?

  - by user340667

  0 Hi - I tried out the Background Image Scaling script and with Cybr's update it works like magic. It SCALES the image perfectly. No distortion. BUT, my image isn't "computer friendly". I.e.: Not 1024 X 768 or even close to that. (Heck, my monitor has a wide screen, so it isn't 1024 X 768 either! Is anybody's anymore?) Anyhow, this creates a problem inasmuch as, unless I size the window from the bottom up it ends up with a white "stripe" beneath it. What I would REALLY like for it to do is have that white to be BLACK. My "usual" BG color/text etc. code is like: ""body bgcolor="#000000" text="#fcba1e" link="#0000ff" vlink="#800080" alink="#ff0000"" (Site won't let me add the arrows here.) I've tried inserting this in various places with no success. Any ideas for a workaround would surely be appreciated ! Thanks ! Bill

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• HTML5: Rendering absolute images using canvas

  - by Mark

  I am experimenting with canvas as part of my HTML5 introduction. This constitutes as assignment work, but I am not asking for any help on the actual coursework at all. I am trying to write a rendering engine, but having no luck because once the image is drawn on canvas it looks very distorted, and not at the right dimensions of the image itself. I have made a animation engine that loads images into an array, and then iterates through them at a certain speed. This is not the problem, and I assume is not causing the issue as this was happening when I drawn an image to the canvas. I think this is natural behaviour for images to be scaled/skewed when the window is resized, so I conquered that by simply redrawing the whole thing once the window is resized. The images I am using are isometric, and drawn at a pixel level. Would this cause the distortion? It seems setting the dimensions on the drawImage() function are not working are all. I am using JavaScript for the manipulation and rendering of the canvas. I would normally try and work it out myself, but I do not have any time to ponder why because I have no idea why it is even scaling/skewing the image once it is drawn on the canvas. I cannot share the code for obvious reasons. I should also mention, the canvas's dimension is the total width of the viewport, as I am developing a game. My question is: Has anyone encountered this and how would I correct it? Thanks for your help.

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• Adobe Photoshop Vs Lightroom Vs Aperture

  - by Aditi

  Adobe Photoshop is the standard choice for photographers, graphic artists and Web designers. Adobe Photoshop Lightroom  & Apple’s Aperture are also in the same league but the usage is vastly different. Although Photoshop is most popular & widely used by photographers, but in many ways it’s less relevant to photographers than ever before. As Lightroom & Aperture is aimed squarely at photographers for photo-processing. With this write up we are going to help you choose what is right for you and why. Adobe Photoshop Adobe Photoshop is the most liked tool for the detailed photo editing & designing work. Photoshop provides great features for rollover and Image slicing. Adobe Photoshop includes comprehensive optimization features for producing the highest quality Web graphics with the smallest possible file sizes. You can also create startling animations with it. Designers & Editors know how important precise masking is, PhotoShop lets you do that with various detailing tools. Art history brush, contact sheets, and history palette are some of the smart features, which add to its viability. Download Whether you’re producing printed pages or moving images, you can work more efficiently and produce better results because of its smooth integration across other adobe applications. Buy supporting layer effects, it allows you to quickly add drop shadows, inner and outer glows, bevels, and embossing to layers. It also provides Seamless Web Graphics Workflow. Photoshop is hands-down the BEST for editing. Photoshop Cons: • Slower, less precise editing features in Bridge • Processing lots of images requires actions and can be slower than exporting images from Lightroom • Much slower with editing and processing a large number of images Aperture Apple Aperture is aimed at the professional photographer who shoots predominantly raw files. It helps them to manage their workflow and perform their initial Raw conversion in a better way. Aperture provides adjustment tools such as Histogram to modify color and white balance, but most of the editing of photos is left for Photoshop. It gives users the option of seeing their photographs laid out like slides or negatives on a light table. It boasts of – stars, color-coding and easy techniques for filtering and picking images. Aperture has moved forward few steps than Photoshop, but most of the editing work has been left for Photoshop as it features seamless Photoshop integration. Aperture Pros: Aperture is a step up from the iPhoto software that comes with every Mac, and fairly easy to learn. Adjustments are made in a logical order from top to bottom of the menu. You can store the images in a library or any folder you choose. Aperture also works really well with direct Canon files. It is just $79 if you buy it through Apple’s App Store Moving forward, it will run on the iPad, and possibly the iPhone – Adobe products like Lightroom and Photoshop may never offer these options It is much nicer and simpler user interface. Lightroom Lightroom does a smashing job of basic fixing and editing. It is more advanced tool for photographers. They can use it to have a startling photography effect. Light room has many advanced features, which makes it one of the best tools for photographers and far ahead of the other two. They are Nondestructive editing. Nothing is actually changed in an image until the photo is exported. Better controls over organizing your photos. Lightroom helps to gather a group of photos to use in a slideshow. Lightroom has larger Compare and Survey views of images. Quickly customizable interface. Simple keystrokes allow you to perform different All Lightroom controls are kept available in panels right next to the photos. Always-available History palette, it doesn’t go when you close lightroom. You gain more colors to work with compared to Photoshop and with more precise control. Local control, or adjusting small parts of a photo without affecting anything else, has long been an important part of photography. In Lightroom 2, you can darken, lighten, and affect color and change sharpness and other aspects of specific areas in the photo simply by brushing your cursor across the areas. Photoshop has far more power in its Cloning and Healing Brush tools than Lightroom, but Lightroom offers simple cloning and healing that’s nondestructive. Lightroom supports the RAW formats of more cameras than Aperture. Lightroom provides the option of storing images outside the application in the file system. It costs less than photoshop. Download Why PhotoShop is advanced than Lightroom? There are countless image processing plug-ins on the market for doing specialized processing in Photoshop. For example, if your image needs sophisticated noise reduction, you can use the Noiseware plug-in with Photoshop to do a much better job or noise removal than Lightroom can do. Lightroom’s advantages over Aperture 3 Will always have better integration with Photoshop. Lightroom is backed by bigger and more active user community (So abundant availability for tutorials, etc.) Better noise reduction tool. Especially for photographers the Lens-distortion correction tool  is perfect Lightroom Cons: • Have to Import images to work on them • Slows down with over 10,000 images in the catalog • For processing just one or two images this is a slower workflow Photoshop Pros: • ACR has the same RAW processing controls as Lightroom • ACR Histogram is specialized to the chosen color space (Lightroom is locked into ProPhoto RGB color space with an sRGB tone curve) • Don’t have to Import images to open in Bridge or ACR • Ability to customize processing of RAW images with Photoshop Actions Pricing and Availability Get LightRoomGet PhotoShop Latest version Of Photoshop can be purchased from Adobe store and Adobe authorized reseller and it costs US$999. Latest version of Aperture can be bought for US$199 from Apple Online store or Mac App Store. You can buy latest version of LightRoom from Adobe Store or Adobe Authorized reseller for US$299. Related posts:Adobe Photoshop CS5 vs Photoshop CS5 extended Web based Alternatives to Photoshop 10 Free Alternatives for Adobe Photoshop Software

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• drawing thick, textured lines in OpenGL

  - by NateS

  I need to draw thick textured line segments in OpenGL. Actually I need curves made out of short line segments. Here is what I have: In the upper left is an example of two connected line segments. The second image shows once the lines are given width, they overlap. If I apply a texture that uses translucency, the overlap looks terrible. The third image shows that both lines are shortened by half the amount necessary to make the thick line corners just touch. This way I can fill the space between the lines with a triangle. On the right you can see this works well (ignore the horizontal line when the crappy texture repeats). But it doesn't always work well. In the bottom left the curve is made of many short line segments. Note the incorrect texture application. My program is written in Java, making use of the LWJGL OpenGL binding (and minor use of Slick, a 2D helper framework). I've made a zip file that contains an executable JAR so you can easily see the problem. It also has the Java code (there is only one source file) and an Eclipse project, so you can instantly run it through Eclipse and hack at it if you like. Here she is: http://n4te.com/temp/lines.zip To run, execute "java -jar lines.jar". You may need "-Djava.library.path=." before -jar if you are not on Windows. Press space to toggle texture/wireframe. The wireframe only shows the line segments, the triangle between them isn't drawn. I don't need to draw arbitrary lines, just bezier curves similar to what you see in the program. Sorry the code is a bit messy, once I have a solution I will refactor. I have investigated using GLUtessellator. It greatly simplified construction of the line, but I found that applying the texture was perfect. It worked most of the time (top image below), but long vertical curves would have severe texture distortion (bottom image below): This turned out to be much easier to code, but in the end worse than my approach. I believe what I'm trying to do is called "line tessellation" or "stroke tessellation". I assume this has been solved already? Is there standard code I can leverage? Otherwise, how can I fix my code so that the texture does not freak out on short, vertical curves?

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• How to display part of an image for the specific width and height?

  - by Brady Chu

  Recently I participated in a web project which has a huge large of images to handle and display on web page, we know that the width and height of images end users uploaded cannot be control easily and then they are hard to display. At first, I attempted to zoom in/out the images to rearch an appropriate presentation, and I made it, but my boss is still not satisfied with my solution, the following is my way: var autoResizeImage = function(maxWidth, maxHeight, objImg) { var img = new Image(); img.src = objImg.src; img.onload = function() { var hRatio; var wRatio; var Ratio = 1; var w = img.width; var h = img.height; wRatio = maxWidth / w; hRatio = maxHeight / h; if (maxWidth == 0 && maxHeight == 0) { Ratio = 1; } else if (maxWidth == 0) { if (hRatio < 1) { Ratio = hRatio; } } else if (maxHeight == 0) { if (wRatio < 1) { Ratio = wRatio; } } else if (wRatio < 1 || hRatio < 1) { Ratio = (wRatio <= hRatio ? wRatio : hRatio); } if (Ratio < 1) { w = w * Ratio; h = h * Ratio; } w = w <= 0 ? 250 : w; h = h <= 0 ? 370 : h; objImg.height = h; objImg.width = w; }; }; This way is only intended to limit the max width and height for the image so that every image in album still has different width and height which are still very urgly. And right at this minute, I know we can create a DIV and use the image as its background image, this way is too complicated and not direct I don't want to take. So I's wondering whether there is a better way to display images with the fixed width and height without presentation distortion? Thanks.

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• Help with dynamic range compression function (audio)

  - by MusiGenesis

  I am writing a C# function for doing dynamic range compression (an audio effect that basically squashes transient peaks and amplifies everything else to produce an overall louder sound). I have written a function that does this (I think): public static void Compress(ref short[] input, double thresholdDb, double ratio) { double maxDb = thresholdDb - (thresholdDb / ratio); double maxGain = Math.Pow(10, -maxDb / 20.0); for (int i = 0; i < input.Length; i += 2) { // convert sample values to ABS gain and store original signs int signL = input[i] < 0 ? -1 : 1; double valL = (double)input[i] / 32768.0; if (valL < 0.0) { valL = -valL; } int signR = input[i + 1] < 0 ? -1 : 1; double valR = (double)input[i + 1] / 32768.0; if (valR < 0.0) { valR = -valR; } // calculate mono value and compress double val = (valL + valR) * 0.5; double posDb = -Math.Log10(val) * 20.0; if (posDb < thresholdDb) { posDb = thresholdDb - ((thresholdDb - posDb) / ratio); } // measure L and R sample values relative to mono value double multL = valL / val; double multR = valR / val; // convert compressed db value to gain and amplify val = Math.Pow(10, -posDb / 20.0); val = val / maxGain; // re-calculate L and R gain values relative to compressed/amplified // mono value valL = val * multL; valR = val * multR; double lim = 1.5; // determined by experimentation, with the goal // being that the lines below should never (or rarely) be hit if (valL > lim) { valL = lim; } if (valR > lim) { valR = lim; } double maxval = 32000.0 / lim; // convert gain values back to sample values input[i] = (short)(valL * maxval); input[i] *= (short)signL; input[i + 1] = (short)(valR * maxval); input[i + 1] *= (short)signR; } } and I am calling it with threshold values between 10.0 db and 30.0 db and ratios between 1.5 and 4.0. This function definitely produces a louder overall sound, but with an unacceptable level of distortion, even at low threshold values and low ratios. Can anybody see anything wrong with this function? Am I handling the stereo aspect correctly (the function assumes stereo input)? As I (dimly) understand things, I don't want to compress the two channels separately, so my code is attempting to compress a "virtual" mono sample value and then apply the same degree of compression to the L and R sample value separately. Not sure I'm doing it right, however. I think part of the problem may the "hard knee" of my function, which kicks in the compression abruptly when the threshold is crossed. I think I may need to use a "soft knee" like this: Can anybody suggest a modification to my function to produce the soft knee curve?

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• DSP - Problems using the inverse Fast Fourier Transform

  - by Trap

  I've been playing around a little with the Exocortex implementation of the FFT, but I'm having some problems. First, after calculating the inverse FFT of an unchanged frequency spectrum obtained by a previous forward FFT, one would expect to get the original signal back, but this is not the case. I had to figure out that I needed to scale the FFT output to about 1 / fftLength to get the amplitudes ok. Why is this? Second, whenever I modify the amplitudes of the frequency bins before calling the iFFT the signal gets distorted at low frequencies. However, this does not happen if I attenuate all the bins by the same factor. Let me put a very simplified example of the output buffer of a 4-sample FFT: // Bin 0 (DC) FFTOut[0] = 0.0000610351563 FFTOut[1] = 0.0 // Bin 1 FFTOut[2] = 0.000331878662 FFTOut[3] = 0.000629425049 // Central bin FFTOut[4] = -0.0000381469727 FFTOut[5] = 0.0 // Bin 3, this is a negative frequency bin. FFTOut[6] = 0.000331878662 FFTOut[7] = -0.000629425049 The output is composed of pairs of floats, each representing the real and imaginay parts of a single bin. So, bin 0 (array indexes 0, 1) would represent the real and imaginary parts of the DC frequency. As you can see, bins 1 and 3 both have the same values, (except for the sign of the Im part), so I guess these are the negative frequency values, and finally indexes (4, 5) would be the central frequency bin. To attenuate the frequency bin 1 this is what I do: // Attenuate the 'positive' bin FFTOut[2] *= 0.5; FFTOut[3] *= 0.5; // Attenuate its corresponding negative bin. FFTOut[6] *= 0.5; FFTOut[7] *= 0.5; For the actual tests I'm using a 1024-length FFT and I always provide all the samples so no 0-padding is needed. // Attenuate var halfSize = fftWindowLength / 2; float leftFreq = 0f; float rightFreq = 22050f; for( var c = 1; c < halfSize; c++ ) { var freq = c * (44100d / halfSize); // Calc. positive and negative frequency locations. var k = c * 2; var nk = (fftWindowLength - c) * 2; // This kind of attenuation corresponds to a high-pass filter. // The attenuation at the transition band is linearly applied, could // this be the cause of the distortion of low frequencies? var attn = (freq < leftFreq) ? 0 : (freq < rightFreq) ? ((freq - leftFreq) / (rightFreq - leftFreq)) : 1; mFFTOut[ k ] *= (float)attn; mFFTOut[ k + 1 ] *= (float)attn; mFFTOut[ nk ] *= (float)attn; mFFTOut[ nk + 1 ] *= (float)attn; } Obviously I'm doing something wrong but can't figure out what or where.

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• DSP - Filtering in the frequency domain via FFT

  - by Trap

  I've been playing around a little with the Exocortex implementation of the FFT, but I'm having some problems. Whenever I modify the amplitudes of the frequency bins before calling the iFFT the resulting signal contains some clicks and pops, especially when low frequencies are present in the signal (like drums or basses). However, this does not happen if I attenuate all the bins by the same factor. Let me put an example of the output buffer of a 4-sample FFT: // Bin 0 (DC) FFTOut[0] = 0.0000610351563 FFTOut[1] = 0.0 // Bin 1 FFTOut[2] = 0.000331878662 FFTOut[3] = 0.000629425049 // Bin 2 FFTOut[4] = -0.0000381469727 FFTOut[5] = 0.0 // Bin 3, this is the first and only negative frequency bin. FFTOut[6] = 0.000331878662 FFTOut[7] = -0.000629425049 The output is composed of pairs of floats, each representing the real and imaginay parts of a single bin. So, bin 0 (array indexes 0, 1) would represent the real and imaginary parts of the DC frequency. As you can see, bins 1 and 3 both have the same values, (except for the sign of the Im part), so I guess bin 3 is the first negative frequency, and finally indexes (4, 5) would be the last positive frequency bin. Then to attenuate the frequency bin 1 this is what I do: // Attenuate the 'positive' bin FFTOut[2] *= 0.5; FFTOut[3] *= 0.5; // Attenuate its corresponding negative bin. FFTOut[6] *= 0.5; FFTOut[7] *= 0.5; For the actual tests I'm using a 1024-length FFT and I always provide all the samples so no 0-padding is needed. // Attenuate var halfSize = fftWindowLength / 2; float leftFreq = 0f; float rightFreq = 22050f; for( var c = 1; c < halfSize; c++ ) { var freq = c * (44100d / halfSize); // Calc. positive and negative frequency indexes. var k = c * 2; var nk = (fftWindowLength - c) * 2; // This kind of attenuation corresponds to a high-pass filter. // The attenuation at the transition band is linearly applied, could // this be the cause of the distortion of low frequencies? var attn = (freq < leftFreq) ? 0 : (freq < rightFreq) ? ((freq - leftFreq) / (rightFreq - leftFreq)) : 1; // Attenuate positive and negative bins. mFFTOut[ k ] *= (float)attn; mFFTOut[ k + 1 ] *= (float)attn; mFFTOut[ nk ] *= (float)attn; mFFTOut[ nk + 1 ] *= (float)attn; } Obviously I'm doing something wrong but can't figure out what. I don't want to use the FFT output as a means to generate a set of FIR coefficients since I'm trying to implement a very basic dynamic equalizer. What's the correct way to filter in the frequency domain? what I'm missing? Thanks in advance.

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