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  • Ho to make Histogram Normalize and Equalize in java using JAI library?

    - by Jay
    I m making App in java using Swing component and JAI library. I make histogram of black and white or gray scale image.Is this method of making histogram correct? iif it is correct then how can i do normalization and Equalization of histogram in my App in java using JAI library?my code is below. in my code i make BufferedImage object and then make and plot histogram of that image . enter code here import java.awt.Color; import java.awt.Graphics; import java.awt.image.BufferedImage; import java.io.IOException; import javax.media.jai.JAI; import javax.media.jai.PlanarImage; import javax.swing.*; public class FinalHistogram extends JPanel { static int[] bins = new int[256]; static int[] newBins = new int[256]; static int x1 = 0, y1 = 0; static PlanarImage image = JAI.create("fileload", "alp_finger.tiff"); static BufferedImage bi = image.getAsBufferedImage(); FinalHistogram(int[] pbins) { for (int i = 0; i < 256; i++) { bins[i] = pbins[i]; newBins[i] = 0; } repaint(); } @Override protected void paintComponent(Graphics g) { for (int i = 0; i < 256; i++) { g.drawLine(150 + i, 300, 150 + i, 300 - (bins[i] / 300)); if (i == 0 || i == 255) { String sr = new Integer((i)).toString(); g.drawString(sr, 150 + i, 305); } System.out.println("bin[" + i + "]===" + bins[i]); } } public static void main(String[] args) throws IOException { int[] sbins = new int[256]; int pixel = 0; int k = 0; for (int x = 0; x < bi.getWidth(); x++) { for (int y = 0; y < bi.getHeight(); y++) { pixel = bi.getRaster().getSample(x, y, 0); k = (int) (pixel / 256); sbins[k]++; //pixel = bi.getRGB(x, y) & 0x000000ff; //k=pixel; //int[] pixels = m_image.getRGB(0, 0, m_image.getWidth(), m_image.getHeight(), null, 0, m_image.getWidth()); //short currentValue = 0; //int red,green,blue; //for(int i = 0; i<pixels.length; i++){ //red = (pixels[i] >> 16) & 0x000000FF; //green = (pixels[i] >>8 ) & 0x000000FF; //blue = pixels[i] & 0x000000FF; //currentValue = (short)((red + green + blue) / 3); //Current value gives the average //Disregard the alpha //assert(currentValue >= 0 && currentValue <= 255); //Something is awfully wrong if this goes off... //m_histogramArray[currentValue] += 1; //Increment the specific value of the array //} } } JTabbedPane jtp = new JTabbedPane(); jtp.addTab("Histogram", new JScrollPane(new FinalHistogram(sbins))); JFrame frame = new JFrame(); frame.setSize(500, 500); frame.add(new JScrollPane(jtp)); frame.setVisible(true); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); } }

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  • Software usage analytics in C#

    - by TiernanO
    I have a project i am working on currently and would like to implement some sort of software tracking in the code. ideally, stuff like how often its launched. how long it runs for, feature tracking, etc. I already use Exceptioneer for unhandled exceptions, but would like something similar for usage tracking. this data should all be anonymous and ideally run as a service by someone else. and i would like to give the users the option to turn it off, if they so wish to... So, is this something i should implement myself, or are there third parties out there that do this sort of things? i know it might be a sticky area, but i have seen stats about iPhone app usage. they do it, so why cant we? (if the user agrees, of course) [Update] Based on the comments, i should have been more clear. this is a Winforms .NET 4. application, though i am thinking of updating it later with WCF. i would only be tracking my own application, though i would also want to know minor information about environment (Windows OS Version, SP, maybe proc and ram...)

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  • Runtime Error 1004 using Select with several workbooks

    - by Johaen
    I have an Excel workbook which pulls out data from two other workbooks. Since the data changes hourly there is the possibility that this macro is used more than one time a day for the same data. So I just want to select all previous data to this date period and want to delete them. Later on the data will be copied in anyway. But as soon as I want to use WBSH.Range(Cells(j, "A"), Cells(lastRow - 1, "M")).Select the code stopes with Error 1004 Application-defined or object-defined error. Followed just a snippet of the code with the relevant part. What is wrong here? 'Set source workbook Dim currentWb As Workbook Set currentWb = ThisWorkbook Set WBSH = currentWb.Sheets("Tracking") 'Query which data from the tracking files shoud get pulled out to the file CheckDate = Application.InputBox(("From which date you want to get data?" & vbCrLf & "Format: yyyy/mm/dd "), "Tracking data", Format(Date - 1, "yyyy/mm/dd")) 'states the last entry which is done ; know where to start ; currentWb File With currentWb.Sheets("Tracking") lastRow = .Range("D" & .Rows.Count).End(xlUp).Row lastRow = lastRow + 1 End With 'just last 250 entries get checked since not so many entries are made in one week j = lastRow - 250 'Check if there is already data to the look up date in the analyses sheet and if so deletes these records Do j = j + 1 'Exit Sub if there is no data to compare to prevent overflow If WBSH.Cells(j + 1, "C").Value = "" Then Exit Do End If Loop While WBSH.Cells(j, "C").Value < CheckDate If j <> lastRow - 1 Then 'WBSH.Range(Cells(j, "A"), Cells(lastRow - 1, "M")).Select 'Selection.ClearContents End If Thank you!

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  • What's the state of the art in image upscaling?

    - by monov
    I like to collect cool pics and use them as wallpapers or for other things. Often, artists publish only low-res versions, probably for fear of theft. Example: Gabriel Pulecio's BIRDS Now, if I want to use that as a wallpaper, I'd have to upscale it, and obviously that'd make it look blurry because of the bicubic interpolation. I realize there's no real way to get a high-res version from a low-res pic, because the information is not simply there. That said, I'm wondering if heuristics have been developed for upscaling with less apparent loss of quality. Those would probably be optimized for specific image types. For photorealistic pictures, for cartoons with large flat areas, for pixel art... One algorithm I'm aware of is Seam Carving. It works for some kinds of pics, especially ones with a plain, undetailed or uninteresting background, and a subject that strongly stands out. But it's far from being general-purpose. Applying it to the above pic produces this. It looks quite sharp, but the proportions are horribly distorted because the algorithm is not designed for this kind of pic. Another is Pixel art scaling algorithms. Those are completely unfit for anything other than actual pixel art that's pixelized to begin with. For example, I tried the scale2x windows binary on my pic, but its output was nearly indistinguishable from nearest-neighbour scaling because the algorithm didn't detect any isolated pixely fragments to work from. Something else I tried was: I enlarged the image in Photoshop with bicubic interpolation, then I applied unsharp mask. The result looks pretty bad. The red blotch is actually resized reasonably well, but the dove is far from it. What I'm looking for is some app that makes a best-effort attempt at upscaling any input image while minimizing blurriness. If you know of any, I'll be thankful. Note that the subjective prettiness and sharpness of the result is what matters... the result doesn't need to be completely faithful to the original small image.

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  • Bad font anti-aliasing in Ubuntu

    - by Juliano
    I'm switching from Fedora 8 to Ubuntu 9.04, and I can't seem to get it to get a good font anti-aliasing to work. It seems that Ubuntu's fontconfig tries to keep characters in integral pixel widths. This makes text more difficult to read, when 1 pixel is too thin and 2 pixels is too thick. Check the image below. In Fedora, when fontconfig anti-aliasing is enabled, fonts have their thickness proportional to the font size. Below, the thickness is different for 8, 9 and 10pt sizes. In Ubuntu, on the other hand, even when anti-aliasing is enabled, all 8, 9 and 10pt sizes have 1 pixel thickness. This makes reading larges amount of text difficult. I'm using the very same home directory, and I already checked that X resources are the same in both systems: ~% xrdb -query | grep Xft Xft.antialias: 1 Xft.dpi: 96 Xft.hinting: 1 Xft.hintstyle: hintfull Xft.rgba: none GNOME settings: ~% gconftool-2 -a /desktop/gnome/font_rendering antialiasing = grayscale hinting = full dpi = 96 rgba_order = rgb So, the question is: What should I change in the new box (Ubuntu) in order to get anti-aliasing like in the old box (Fedora)?

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  • Calculating and billing IP multicast usage on the Internet

    - by obvio171
    I've been searching for the reasons why IP multicast isn't widely supported on the Public Internet, and a commonly-cited reason is the difficulty ISPs have in tracking Multicast usage for later billing. Given this difficulty, since ISPs control the routers and they're not forced to support Multicast (as per IPv4), they just disable it. I couldn't find what this difficulty was though. Since an ISP has full control of any inbound and outbound traffic, be it Unicast or Multicast, what's the difficulty in tracking and billing the latter that does not exist in the former?

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  • Google analytics and multiple independent subdomains

    - by MTilsted
    I need some help trying to setup google analytics correct. Here is my setup: We host sites for multiple customers, and each customer have their own subdomain on our site. So we have customerA.oursite.com and customerB.oursite.com As we add more customers we get more subdomains. We do want to track all data for each customer independent, but I don't want to to create a new google tracking code for each new customer. So my plan is to track all visits with "oursite.com", and then I will create a filter in google Analytics to get data for each specific customer(All visits for a specific subdomain). Is this(One tracking code, and a subdomain filter) the right way to do it? To create a subdomain filter i add a new profile for each customer, and then add a custom filter saying include "Request URI" and fill in "CustomerDomain.oursite.com". Is this the correct way to do it? And a general question about filters: Is it really impossible to create a new filter by applying it to data in an existing profile? I would really like to just collect all the data in one "main" profile and then create subdomain filters as we need them. But it seems that google only apply filters to new incomming data, not existing data. Is this really true? The following is my tracking code. Is '_setDomainName','none' the right thing to do? <script type="text/javascript"> /* Tracking code for qrtown.com */ var _gaq = _gaq || []; _gaq.push(['_setAccount', 'UA-11584298-10']); _gaq.push(['_setDomainName', 'none']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); </script>

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  • How to create issue dependencies/links in Jira (3.13) ?

    - by zarko.susnjar
    Hi, We recently switched from other bug tracking software to Jira (3.13 currently ). We need to set issue linking in a manner that my task start time depends on other colleague's issue and I can not start until he resolves his issue... I goolged and found that this kind of thing is integrated in newer versions :/ Maybe we need some plugin, make some custom field, enable something in administration part... Any help would be appreciated... (please retag/add jira and bug-tracking tags or whatever)

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  • Java: Send BufferedImage through Socket with a low bitdepth

    - by Martijn Courteaux
    Hi, The title says enough I think. I have a full quality BufferedImage and I want to send it through an OutputStream with a low bitdepth. I don't want an algorithm to change pixel by pixel the quality, so it is still a full-quality. So, the goal is to write the image (with the full resolution) through the OuputStream with a very small size. Thanks, Martijn

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  • Font Anti-Aliasing on iPad SDK

    - by Felix Khazin
    I'm using a custom pixel font on the iPad SDK, and I'm trying to find a way to disable font anti-aliasing for UIFont. Pixel fonts usually work best when they don't have Anti-aliasing. I disable it easily in Photoshop when I create static resources, but this time I need a dynamic output with the custom font. Any ideas? Thanks.

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  • How to make ARGB transparency using bitwise operators.

    - by Smejda
    I need to make transparency, having 2 pixels: pixel1: {A, R, G, B} - foreground pixel pixel2: {A, R, G, B} - background pixel A,R,G,B are Byte values each color is represented by byte value now I'm calculating transparency as: newR = pixel2_R * alpha / 255 + pixel1_R * (255 - alpha) / 255 newG = pixel2_G * alpha / 255 + pixel1_G * (255 - alpha) / 255 newB = pixel2_B * alpha / 255 + pixel1_B * (255 - alpha) / 255 but it is too slow I need to do it with bitwise operators (AND,OR,XOR, NEGATION, BIT MOVE)

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  • Centering a percent-based div

    - by Sarfraz
    Hello, Recently, a client asked that his site be percent-based rather than pixel-based. The percent was to be set to 80%. As you guys know, it is very easy to center the container if it is pixel-based but how do you center a percent-based main container? #container { width:80%; margin:0px auto; } That does not center the container :(

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  • AVFoundation buffer comparison to a saved image

    - by user577552
    Hi, I am a long time reader, first time poster on StackOverflow, and must say it has been a great source of knowledge for me. I am trying to get to know the AVFoundation framework. What I want to do is save what the camera sees and then detect when something changes. Here is the part where I save the image to a UIImage : if (shouldSetBackgroundImage) { CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); // Create a bitmap graphics context with the sample buffer data CGContextRef context = CGBitmapContextCreate(rowBase, bufferWidth, bufferHeight, 8, bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst); // Create a Quartz image from the pixel data in the bitmap graphics context CGImageRef quartzImage = CGBitmapContextCreateImage(context); // Free up the context and color space CGContextRelease(context); CGColorSpaceRelease(colorSpace); // Create an image object from the Quartz image UIImage * image = [UIImage imageWithCGImage:quartzImage]; [self setBackgroundImage:image]; NSLog(@"reference image actually set"); // Release the Quartz image CGImageRelease(quartzImage); //Signal that the image has been saved shouldSetBackgroundImage = NO; } and here is the part where I check if there is any change in the image seen by the camera : else { CGImageRef cgImage = [backgroundImage CGImage]; CGDataProviderRef provider = CGImageGetDataProvider(cgImage); CFDataRef bitmapData = CGDataProviderCopyData(provider); char* data = CFDataGetBytePtr(bitmapData); if (data != NULL) { int64_t numDiffer = 0, pixelCount = 0; NSMutableArray * pointsMutable = [NSMutableArray array]; for( int row = 0; row < bufferHeight; row += 8 ) { for( int column = 0; column < bufferWidth; column += 8 ) { //we get one pixel from each source (buffer and saved image) unsigned char *pixel = rowBase + (row * bytesPerRow) + (column * BYTES_PER_PIXEL); unsigned char *referencePixel = data + (row * bytesPerRow) + (column * BYTES_PER_PIXEL); pixelCount++; if ( !match(pixel, referencePixel, matchThreshold) ) { numDiffer++; [pointsMutable addObject:[NSValue valueWithCGPoint:CGPointMake(SCREEN_WIDTH - (column/ (float) bufferHeight)* SCREEN_WIDTH - 4.0, (row/ (float) bufferWidth)* SCREEN_HEIGHT- 4.0)]]; } } } numberOfPixelsThatDiffer = numDiffer; points = [pointsMutable copy]; } For some reason, this doesn't work, meaning that the iPhone detects almost everything as being different from the saved image, even though I set a very low threshold for detection in the match function... Do you have any idea of what I am doing wrong?

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  • Use native HBitmap in C# while preserving alpha channel/transparency. Please check this code, it works on my computer...

    - by David
    Let's say I get a HBITMAP object/handle from a native Windows function. I can convert it to a managed bitmap using Bitmap.FromHbitmap(nativeHBitmap), but if the native image has transparency information (alpha channel), it is lost by this conversion. There are a few questions on Stack Overflow regarding this issue. Using information from the first answer of this question (How to draw ARGB bitmap using GDI+?), I wrote a piece of code that I've tried and it works. It basically gets the native HBitmap width, height and the pointer to the location of the pixel data using GetObject and the BITMAP structure, and then calls the managed Bitmap constructor: Bitmap managedBitmap = new Bitmap(bitmapStruct.bmWidth, bitmapStruct.bmHeight, bitmapStruct.bmWidth * 4, PixelFormat.Format32bppArgb, bitmapStruct.bmBits); As I understand (please correct me if I'm wrong), this does not copy the actual pixel data from the native HBitmap to the managed bitmap, it simply points the managed bitmap to the pixel data from the native HBitmap. And I don't draw the bitmap here on another Graphics (DC) or on another bitmap, to avoid unnecessary memory copying, especially for large bitmaps. I can simply assign this bitmap to a PictureBox control or the the Form BackgroundImage property. And it works, the bitmap is displayed correctly, using transparency. When I no longer use the bitmap, I make sure the BackgroundImage property is no longer pointing to the bitmap, and I dispose both the managed bitmap and the native HBitmap. The Question: Can you tell me if this reasoning and code seems correct. I hope I will not get some unexpected behaviors or errors. And I hope I'm freeing all the memory and objects correctly. private void Example() { IntPtr nativeHBitmap = IntPtr.Zero; /* Get the native HBitmap object from a Windows function here */ // Create the BITMAP structure and get info from our nativeHBitmap NativeMethods.BITMAP bitmapStruct = new NativeMethods.BITMAP(); NativeMethods.GetObjectBitmap(nativeHBitmap, Marshal.SizeOf(bitmapStruct), ref bitmapStruct); // Create the managed bitmap using the pointer to the pixel data of the native HBitmap Bitmap managedBitmap = new Bitmap( bitmapStruct.bmWidth, bitmapStruct.bmHeight, bitmapStruct.bmWidth * 4, PixelFormat.Format32bppArgb, bitmapStruct.bmBits); // Show the bitmap this.BackgroundImage = managedBitmap; /* Run the program, use the image */ MessageBox.Show("running..."); // When the image is no longer needed, dispose both the managed Bitmap object and the native HBitmap this.BackgroundImage = null; managedBitmap.Dispose(); NativeMethods.DeleteObject(nativeHBitmap); } internal static class NativeMethods { [StructLayout(LayoutKind.Sequential)] public struct BITMAP { public int bmType; public int bmWidth; public int bmHeight; public int bmWidthBytes; public ushort bmPlanes; public ushort bmBitsPixel; public IntPtr bmBits; } [DllImport("gdi32", CharSet = CharSet.Auto, EntryPoint = "GetObject")] public static extern int GetObjectBitmap(IntPtr hObject, int nCount, ref BITMAP lpObject); [DllImport("gdi32.dll")] internal static extern bool DeleteObject(IntPtr hObject); }

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  • How to play YUV video in Qt4?

    - by shingle
    I want to play YUV video sequence by using Qt. Now I am using QPixmap, by using DrawPixel on QPixmap pixel by pixel. However, it can't play the video in real-time. How can I do to improve the speed?

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  • How can I get image data from QTKit without color or gamma correction in Snow Leopard?

    - by Nick Haddad
    Since Snow Leopard, QTKit is now returning color corrected image data from functions like QTMovies frameImageAtTime:withAttributes:error:. Given an uncompressed AVI file, the same image data is displayed with larger pixel values in Snow Leopard vs. Leopard. Currently I'm using frameImageAtTime to get an NSImage, then ask for the tiffRepresentation of that image. After doing this, pixel values are slightly higher in Snow Leopard. For example, a file with the following pixel value in Leopard: [0 180 0] Now has a pixel value like: [0 192 0] Is there any way to ask a QTMovie for video frames that are not color corrected? Should I be asking for a CGImageRef, CIImage, or CVPixelBufferRef instead? Is there a way to disable color correction altogether prior to reading in the video files? I've attempted to work around this issue by drawing into a NSBitmapImageRep with the NSCalibratedColroSpace, but that only gets my part of the way there: // Create a movie NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys : nsFileName, QTMovieFileNameAttribute, [NSNumber numberWithBool:NO], QTMovieOpenAsyncOKAttribute, [NSNumber numberWithBool:NO], QTMovieLoopsAttribute, [NSNumber numberWithBool:NO], QTMovieLoopsBackAndForthAttribute, (id)nil]; _theMovie = [[QTMovie alloc] initWithAttributes:dict error:&error]; // .... NSMutableDictionary *imageAttributes = [NSMutableDictionary dictionary]; [imageAttributes setObject:QTMovieFrameImageTypeNSImage forKey:QTMovieFrameImageType]; [imageAttributes setObject:[NSArray arrayWithObject:@"NSBitmapImageRep"] forKey: QTMovieFrameImageRepresentationsType]; [imageAttributes setObject:[NSNumber numberWithBool:YES] forKey:QTMovieFrameImageHighQuality]; NSError* err = nil; NSImage* image = (NSImage*)[_theMovie frameImageAtTime:frameTime withAttributes:imageAttributes error:&err]; // copy NSImage into an NSBitmapImageRep (Objective-C) NSBitmapImageRep* bitmap = [[image representations] objectAtIndex:0]; // Draw into a colorspace we know about NSBitmapImageRep *bitmapWhoseFormatIKnow = [[NSBitmapImageRep alloc] initWithBitmapDataPlanes:NULL pixelsWide:getWidth() pixelsHigh:getHeight() bitsPerSample:8 samplesPerPixel:4 hasAlpha:YES isPlanar:NO colorSpaceName:NSCalibratedRGBColorSpace bitmapFormat:0 bytesPerRow:(getWidth() * 4) bitsPerPixel:32]; [NSGraphicsContext saveGraphicsState]; [NSGraphicsContext setCurrentContext:[NSGraphicsContext graphicsContextWithBitmapImageRep:bitmapWhoseFormatIKnow]]; [bitmap draw]; [NSGraphicsContext restoreGraphicsState]; This does convert back to a 'Non color corrected' colorspace, but the color values NOT are exactly the same as what is stored in the Uncompressed AVI files we are testing with. Also this is much less efficient because it is converting from RGB - "Device RGB" - RGB. Also, I am working in a 64-bit application, so dropping down to the Quicktime-C API is not an option. Thanks for your help.

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  • AS3 Transition Manager problem

    - by Mirko
    I am using the TransitionManager class to pixel dissolve an image in an image gallery XML driven. It always stops half way through the animation...I hate Adobe Tween engines, I always used TweenMax without (almost) any problem but I would like to have the pixel dissolve effect. var myTM:TransitionManager = new TransitionManager(container_mc); myTM.addEventListener("allTransitionsOutDone",swapContent); myTM.startTransition({ type:PixelDissolve, direction:Transition.OUT, duration:1,easing:None.easeOut,xSections:200, ySections:200 }); Any suggestion?

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  • Performance Optimization for Matrix Rotation

    - by Summer_More_More_Tea
    Hello everyone: I'm now trapped by a performance optimization lab in the book "Computer System from a Programmer's Perspective" described as following: In a N*N matrix M, where N is multiple of 32, the rotate operation can be represented as: Transpose: interchange elements M(i,j) and M(j,i) Exchange rows: Row i is exchanged with row N-1-i A example for matrix rotation(N is 3 instead of 32 for simplicity): ------- ------- |1|2|3| |3|6|9| ------- ------- |4|5|6| after rotate is |2|5|8| ------- ------- |7|8|9| |1|4|7| ------- ------- A naive implementation is: #define RIDX(i,j,n) ((i)*(n)+(j)) void naive_rotate(int dim, pixel *src, pixel *dst) { int i, j; for (i = 0; i < dim; i++) for (j = 0; j < dim; j++) dst[RIDX(dim-1-j, i, dim)] = src[RIDX(i, j, dim)]; } I come up with an idea by inner-loop-unroll. The result is: Code Version Speed Up original 1x unrolled by 2 1.33x unrolled by 4 1.33x unrolled by 8 1.55x unrolled by 16 1.67x unrolled by 32 1.61x I also get a code snippet from pastebin.com that seems can solve this problem: void rotate(int dim, pixel *src, pixel *dst) { int stride = 32; int count = dim >> 5; src += dim - 1; int a1 = count; do { int a2 = dim; do { int a3 = stride; do { *dst++ = *src; src += dim; } while(--a3); src -= dim * stride + 1; dst += dim - stride; } while(--a2); src += dim * (stride + 1); dst -= dim * dim - stride; } while(--a1); } After carefully read the code, I think main idea of this solution is treat 32 rows as a data zone, and perform the rotating operation respectively. Speed up of this version is 1.85x, overwhelming all the loop-unroll version. Here are the questions: In the inner-loop-unroll version, why does increment slow down if the unrolling factor increase, especially change the unrolling factor from 8 to 16, which does not effect the same when switch from 4 to 8? Does the result have some relationship with depth of the CPU pipeline? If the answer is yes, could the degrade of increment reflect pipeline length? What is the probable reason for the optimization of data-zone version? It seems that there is no too much essential difference from the original naive version. EDIT: My test environment is Intel Centrino Duo processor and the verion of gcc is 4.4 Any advice will be highly appreciated! Kind regards!

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  • Compare values for audit trail

    - by kagaku
    I'm attempting to develop an audit trail/tracking solution for an existing database written in PLSQL/PHP - however I'm still unsure as of yet on an easy (to implement and maintain) solution for tracking changes to fields/values. For instance, the project tracking portion of the DB APP tracks over 200 fields and ideally I'd like a nice way to show a history of changes, such as: 5/10/2010 - Project 435232 updated by John Doe Changed Project Name (Old: Test Project; New: Super Test Project) Changed Submission Date (Old: 5/10/2010; New: 5/11/2010) Changed Description (Old: This is an example!; New: This is a test example) Essentially for each field (db column) it would output a new line to show the old/new values. So far my current idea is saving the current version of the data to a temporary table, updating the primary table with the new data then loading each row into an array and doing an array compare to determine the differences. This seems a bit convoluted, and if there is an easier method I'd love to know it. Any ideas or suggestions are much appreciated!

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  • How to tile a 30000 x 6000 image for a 480 x 320 screen?

    - by Horace Ho
    (this is related to another question about implementation on iPhone) I have a large image, size around 30000 (w) x 6000 (h) pixels. You may consider it's like a big map. I assume I need to crop it up into smaller tiles. Questions: what is the tile strategy? Requirements: whole image (though cropped) can be scrolled up/down/left/right by swipes zoom in (up to pixel-to-pixel) out (down to screen-fit-by-height) by the 2-finger operation memory efficiency by lazy loading tiles Thanks!

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  • Why do I get rows of zeros in my 2D fft?

    - by Nicholas Pringle
    I am trying to replicate the results from a paper. "Two-dimensional Fourier Transform (2D-FT) in space and time along sections of constant latitude (east-west) and longitude (north-south) were used to characterize the spectrum of the simulated flux variability south of 40degS." - Lenton et al(2006) The figures published show "the log of the variance of the 2D-FT". I have tried to create an array consisting of the seasonal cycle of similar data as well as the noise. I have defined the noise as the original array minus the signal array. Here is the code that I used to plot the 2D-FT of the signal array averaged in latitude: import numpy as np from numpy import ma from matplotlib import pyplot as plt from Scientific.IO.NetCDF import NetCDFFile ### input directory indir = '/home/nicholas/data/' ### get the flux data which is in ### [time(5day ave for 10 years),latitude,longitude] nc = NetCDFFile(indir + 'CFLX_2000_2009.nc','r') cflux_southern_ocean = nc.variables['Cflx'][:,10:50,:] cflux_southern_ocean = ma.masked_values(cflux_southern_ocean,1e+20) # mask land nc.close() cflux = cflux_southern_ocean*1e08 # change units of data from mmol/m^2/s ### create an array that consists of the seasonal signal fro each pixel year_stack = np.split(cflux, 10, axis=0) year_stack = np.array(year_stack) signal_array = np.tile(np.mean(year_stack, axis=0), (10, 1, 1)) signal_array = ma.masked_where(signal_array > 1e20, signal_array) # need to mask ### average the array over latitude(or longitude) signal_time_lon = ma.mean(signal_array, axis=1) ### do a 2D Fourier Transform of the time/space image ft = np.fft.fft2(signal_time_lon) mgft = np.abs(ft) ps = mgft**2 log_ps = np.log(mgft) log_mgft= np.log(mgft) Every second row of the ft consists completely of zeros. Why is this? Would it be acceptable to add a randomly small number to the signal to avoid this. signal_time_lon = signal_time_lon + np.random.randint(0,9,size=(730, 182))*1e-05 EDIT: Adding images and clarify meaning The output of rfft2 still appears to be a complex array. Using fftshift shifts the edges of the image to the centre; I still have a power spectrum regardless. I expect that the reason that I get rows of zeros is that I have re-created the timeseries for each pixel. The ft[0, 0] pixel contains the mean of the signal. So the ft[1, 0] corresponds to a sinusoid with one cycle over the entire signal in the rows of the starting image. Here are is the starting image using following code: plt.pcolormesh(signal_time_lon); plt.colorbar(); plt.axis('tight') Here is result using following code: ft = np.fft.rfft2(signal_time_lon) mgft = np.abs(ft) ps = mgft**2 log_ps = np.log1p(mgft) plt.pcolormesh(log_ps); plt.colorbar(); plt.axis('tight') It may not be clear in the image but it is only every second row that contains completely zeros. Every tenth pixel (log_ps[10, 0]) is a high value. The other pixels (log_ps[2, 0], log_ps[4, 0] etc) have very low values.

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