Related
I'm working on an application that can encrypt and decrypt an image (specific selection ) using RSA algorithm, all works well but some pixels are behaving strangely and I can't understand why! I use the same parameters to encrypt/decrypt and save the image and yet, when I create the new image, and try to read the pixels in crypted zone, I don't get the pixel that my program showed me before.
File img = new File (Path);
bf1 = ImageIO.read(img);
marchdanslImage(bf1,captureRect); // only selected rectangle (captureRect) from image will be treated
///////the function i called before
private void marchdanslImage(BufferedImage image , Rectangle REC) throws IOException {
bf2 = new BufferedImage(REC.width, REC.height, BufferedImage.TYPE_INT_RGB); //this image gonna contain the pixels after encryption
for (int i = y; i < h; i++) {
for (int j = x; j < w; j++) {
int pixel = image.getRGB(j, i);//orginal values
printPixelARGB(pixel,j,i); //here i call the code to crypt or decrypt
bf2.setRGB(j-x,i-y, rgb); //new values
} }
}
the code of the function printPixelARGB:
public void printPixelARGB(int pixel,int i , int j) {
r[i][j] = (pixel >> 16) & 0xff; // original values
rr[i][j] = RSA_crypt_decrypt(r[i][j], appel);//values after treatment
g[i][j] = (pixel >> 8) & 0xff;
gg[i][j] = RSA_crypt_decrypt(g[i][j], appel);
b[i][j] = (pixel) & 0xff;
bb[i][j] = RSA_crypt_decrypt(b[i][j], appel);
rgb = rr[i][j];// new values on rgb to be set in bf2
rgb = (rgb << 8) + gg[i][j];
rgb = (rgb << 8) + bb[i][j];
}
and finally to save my work:
public void save_image()
{
Graphics2D g;
g = (Graphics2D) bf1.getGraphics();
g.drawImage(bf2, captureRect.x, captureRect.y, captureRect.width, captureRect.height, null);
g.dispose();
//i draw the crypted pixels on my original image and create new image
File outputFile = new File("C:/USERS/HP/DesKtop/output.jpg");
try {
ImageIO.write(bf1, "jpg", outputFile);
} catch (IOException ex) {
Logger.getLogger(MenuGenerale2.class.getName()).log(Level.SEVERE, null, ex);
}
}
So far everything is working, but when open the image I created, and try to decrypt, the values I get are not the same, after treatment!
Is it because of the saving part? When I try it on a white image it does not work correctly, but on another image it does not at all! It's been 3 weeks couldn't solve this problem... I really really need help.
Here is the link of my application:
www.fichier-rar.fr/2016/04/23/cryptagersa11/
The problem is that you are saving the image with JPEG compression. JPEG compression does not preserve data exactly: it is a lossy compression.
If you used, say, BMP or PNG files, the problem would would not happen.
You might want to investigate steganography, although I suspect it is the opposite of what you want to achieve
Sorry for asking a really basic question, but it's probably the first time for a number of years I feel really confused.
Windows provides two set of controls: Windows.UI.Xaml namespace (I thinks this is referred as Metro), used for Windows Store Apps, and System.Windows (WPF) for Desktop.
Since I am going to develop Windows Store Apps mainly for Windows 8.1 and Windows 10 phones, I will have to stick to Windows.UI.Xaml, and this has not only a separate set of UI elements, but also separate set of bitmaps, brushes, etc. (Windows.UI.Xaml.Media vs System.Windows.Media).
I found that Windows.UI.Xaml provides a very limited support for graphics, much less than provided by WPF, Android or (even!) iOS platform. To start with, I got stuck with a simple task: tiling a background!
Since Windows.UI.Xaml.Media.ImageBrush do not support tiling, I wanted to to do that "manually". Some sites suggest making numerous number of children, each holding a tile. Honestly, it looks as a rather awkward approach to me, so I decided to do it in what appears a more natural way: create an off-screen tiled image, assign it to a brush and assign the brush as the background for a panel.
The tiling code is rather straightforward (it probably has mistakes, possibly won't even not run on a phone, because of some unavailable classes used).
int panelWidth = (int) contentPanel.Width;
int panelHeight = (int) contentPanel.Height;
Bitmap bmpOffscreen = new Bitmap(panelWidth, panelHeight);
Graphics gOffscreen = Graphics.FromImage(bmpOffscreen);
string bmpPath = Path.Combine(Windows.ApplicationModel.Package.Current.InstalledLocation.Path, "Assets/just_a_tile.png");
System.Drawing.Image tile = System.Drawing.Image.FromFile(bmpPath, true);
int tileWidth = tile.Width;
int tileHeight = tile.Height;
for (int y = 0; y < panelHeight; y += tileHeight)
for (int x = 0; x < panelWidth; x += tileWidth)
gOffscreen.DrawImage(tile, x, y);
Now I presumably have the tiled image in bmpOffscreen. But how assign it to a brush? To do that I need to convert Bitmap to BitmapSource, while I couldn't find something similar to System.Windows.Imaging.CreateBitmapSourceFromHBitmap available for WPF structure!
Well, first of all System.Drawing namespace is not available in Windows Universal Platform, so you won't be able to use Bitmap class
But, all hope is not lost - you can use
Windows.UI.Xaml.Media.Imaging.WriteableBitmap
If you look at example included on this page, you will see that at one point image data is extracted to a byte array - all you need to do is copy it according to your needs
Please let me know if you want me to include a complete code sample.
Edit:
StorageFile file = await StorageFile.GetFileFromPathAsync(filePath);
Scenario4WriteableBitmap = new WriteableBitmap(2000, 2000);
// Ensure a file was selected
if (file != null)
{
using (IRandomAccessStream fileStream = await file.OpenAsync(Windows.Storage.FileAccessMode.Read))
{
int columns = 4;
int rows = 4;
BitmapDecoder decoder = await BitmapDecoder.CreateAsync(fileStream);
// Scale image to appropriate size
BitmapTransform transform = new BitmapTransform()
{
ScaledHeight = Convert.ToUInt32(Scenario4ImageContainer.Height),
ScaledWidth = Convert.ToUInt32(Scenario4ImageContainer.Width)
};
PixelDataProvider pixelData = await decoder.GetPixelDataAsync(
BitmapPixelFormat.Bgra8, // WriteableBitmap uses BGRA format
BitmapAlphaMode.Straight,
transform,
ExifOrientationMode.IgnoreExifOrientation, // This sample ignores Exif orientation
ColorManagementMode.DoNotColorManage);
// An array containing the decoded image data, which could be modified before being displayed
byte[] sourcePixels = pixelData.DetachPixelData();
// Open a stream to copy the image contents to the WriteableBitmap's pixel buffer
using (Stream stream = Scenario4WriteableBitmap.PixelBuffer.AsStream())
{
for (int i = 0; i < columns * rows; i++)
{
await stream.WriteAsync(sourcePixels, 0, sourcePixels.Length);
}
}
}
// Redraw the WriteableBitmap
Scenario4WriteableBitmap.Invalidate();
Scenario4Image.Source = Scenario4WriteableBitmap;
Scenario4Image.Stretch = Stretch.None;
}
Thank you, Arkadiusz. Since Australian time goes slightly ahead of Europe,
I had an advantage and seen the code before you posted it. I downloaded
MSDN XAML images sample and it helped me a lot. I gave a +1 to you but someone apparently put -1, so it compensated each other. Don't be upset I get -1 so often, that I stopped paying attention on that :)
So I've managed to do tiling with Windows Universal Platform! On my Lumia 532 phone it works magnifique. I felt like re-inventing a wheel, because all this stuff must be handled by SDK, not by a third-party developer.
public static async Task<bool> setupTiledBackground(Panel panel, string tilePath)
{
Brush backgroundBrush = await createTiledBackground((int)panel.Width, (int)panel.Height, TilePath);
if (backgroundBrush == null) return false;
panel.Background = backgroundBrush;
return true;
}
private static async Task<Brush> createTiledBackground(int width, int height, string tilePath)
{
StorageFile file = await StorageFile.GetFileFromApplicationUriAsync(new Uri("ms-appx:///" + tilePath));
byte[] sourcePixels;
int tileWidth, tileHeight;
using (IRandomAccessStream inputStream = await file.OpenAsync(Windows.Storage.FileAccessMode.Read))
{
if (inputStream == null) return null;
BitmapDecoder tileDecoder = await BitmapDecoder.CreateAsync(inputStream);
if (tileDecoder == null) return null;
tileWidth = (int)tileDecoder.PixelWidth;
tileHeight = (int) tileDecoder.PixelHeight;
PixelDataProvider pixelData = await tileDecoder.GetPixelDataAsync(
BitmapPixelFormat.Bgra8, // WriteableBitmap uses BGRA format
BitmapAlphaMode.Straight,
new BitmapTransform(),
ExifOrientationMode.IgnoreExifOrientation,
ColorManagementMode.DoNotColorManage);
sourcePixels = pixelData.DetachPixelData();
// fileStream.Dispose();
}
WriteableBitmap backgroundBitmap = new WriteableBitmap(width, height);
int tileBmpWidth = tileWidth << 2;
int screenBmpWidth = width << 2;
int tileSize = tileBmpWidth * tileHeight;
int sourceOffset = 0;
using (Stream outputStream = backgroundBitmap.PixelBuffer.AsStream())
{
for (int bmpY=0; bmpY < height; bmpY++) {
for (int bmpX = 0; bmpX < screenBmpWidth; bmpX += tileBmpWidth)
await outputStream.WriteAsync(sourcePixels, sourceOffset, Math.Min(screenBmpWidth - bmpX, tileBmpWidth));
if ((sourceOffset += tileBmpWidth) >= tileSize)
sourceOffset -= tileSize;
}
}
ImageBrush backgroundBrush = new ImageBrush();
backgroundBrush.ImageSource = backgroundBitmap; // It's very easy now!
return backgroundBrush; // Finita la comédia!
}
Just one remark: if you do it on form start, you should not wait for it.
This doesn't work:
public MainPage()
{
this.InitializeComponent();
bool result = setupTiledBackground(contextPanel, TilePath).Result;
}
This works:
private Task<bool> backgroundImageTask;
public MainPage()
{
this.InitializeComponent();
backgroundImageTask = setupTiledBackground(contextPanel, TilePath);
}
It seems like this should be simpler than I'm finding it to be.
I have an AVFoundation frame coming back in the standard delegate method:
- (void)captureOutput:(AVCaptureOutput *)captureOutput
didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
fromConnection:(AVCaptureConnection *)connection
where I would like to convert the frame to greyscale using the Accelerate.Framework.
There is a family of conversion methods in the framework, including vImageConvert_RGBA8888toPlanar8(), which looks like it might be what I would like to see, however, I can't find any examples of how to use them!
So far, I have the code:
- (void)captureOutput:(AVCaptureOutput *)captureOutput
didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
fromConnection:(AVCaptureConnection *)connection
{
#autoreleasepool {
CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
/*Lock the image buffer*/
CVPixelBufferLockBaseAddress(imageBuffer,0);
/*Get information about the image*/
uint8_t *baseAddress = (uint8_t *)CVPixelBufferGetBaseAddress(imageBuffer);
size_t width = CVPixelBufferGetWidth(imageBuffer);
size_t height = CVPixelBufferGetHeight(imageBuffer);
size_t stride = CVPixelBufferGetBytesPerRow(imageBuffer);
// vImage In
Pixel_8 *bitmap = (Pixel_8 *)malloc(width * height * sizeof(Pixel_8));
const vImage_Buffer inImage = { bitmap, height, width, stride };
//How can I take this inImage and convert it to greyscale?????
//vImageConvert_RGBA8888toPlanar8()??? Is the correct starting format here??
}
}
So I have two questions:
(1) In the code above, is RBGA8888 the correct starting format?
(2) How can I actually make the Accelerate.Framework call to convert to greyscale?
There is an easier option here. If you change the camera acquire format to YUV, then you already have a greyscale frame that you can use as you like. When setting up your data output, use something like:
dataOutput.videoSettings = #{ (id)kCVPixelBufferPixelFormatTypeKey : #(kCVPixelFormatType_420YpCbCr8BiPlanarFullRange) };
You can then access the Y plane in your capture callback using:
CVPixelBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
CVPixelBufferLockBaseAddress(pixelBuffer, kCVPixelBufferLock_ReadOnly);
uint8_t *yPlane = CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 0);
... do stuff with your greyscale camera image ...
CVPixelBufferUnlockBaseAddress(pixelBuffer);
The vImage method is to use vImageMatrixMultiply_Planar8 and a 1x3 matrix.
vImageConvert_RGBA8888toPlanar8 is the function you use to convert a RGBA8888 buffer into 4 planar buffers. These are used by vImageMatrixMultiply_Planar8. vImageMatrixMultiply_ARGB8888 will do it too in one pass, but your gray channel will be interleaved with three other channels in the result. vImageConvert_RGBA8888toPlanar8 itself doesn't do any math. All it does is separate your interleaved image into separate image planes.
If you need to adjust the gamma as well, then probably vImageConvert_AnyToAny() is the easy choice. It will do the fully color managed conversion from your RGB format to a grayscale colorspace. See vImage_Utilities.h.
I like Tarks answer better though. It just leaves you in a position of having to color manage the Luminance manually (if you care).
Convert BGRA Image to Grayscale with Accelerate vImage
This method is meant to illustrate getting Accelerate's vImage use in converting BGR images to grayscale. Your image may very well be in RGBA format and you'll need to adjust the matrix accordingly, but the camera outputs BGRA so I'm using it here. The values in the matrix are the same values used in OpenCV for cvtColor, there are other values you might play with like luminosity. I assume you malloc the appropriate amount of memory for the result. In the case of grayscale it is only 1-channel or 1/4 the memory used for BGRA. If anyone finds issues with this code please leave a comment.
Performance note
Converting to grayscale in this way may NOT be the fastest. You should check the performance of any method in your environment. Brad Larson's GPUImage might be faster, or even OpenCV's cvtColor. In any case you will want to remove the calls to malloc and free for the intermediate buffers and manage them for the app lifecycle. Otherwise, the function call will be dominated by the malloc and free. Apple's docs recommend reusing the whole vImage_Buffer when possible.
You can also read about solving the same problem with NEON intrinsics.
Finally, the fastest method is not converting at all. If you're getting image data from the device camera the device camera is natively in the kCVPixelFormatType_420YpCbCr8BiPlanarFullRange format. Meaning, grabbing the first plane's data (Y-Channel, luma) is the fastest way to get grayscale.
BGRA to Grayscale
- (void)convertBGRAFrame:(const CLPBasicVideoFrame &)bgraFrame toGrayscale:(CLPBasicVideoFrame &)grayscaleFrame
{
vImage_Buffer bgraImageBuffer = {
.width = bgraFrame.width,
.height = bgraFrame.height,
.rowBytes = bgraFrame.bytesPerRow,
.data = bgraFrame.rawPixelData
};
void *intermediateBuffer = malloc(bgraFrame.totalBytes);
vImage_Buffer intermediateImageBuffer = {
.width = bgraFrame.width,
.height = bgraFrame.height,
.rowBytes = bgraFrame.bytesPerRow,
.data = intermediateBuffer
};
int32_t divisor = 256;
// int16_t a = (int16_t)roundf(1.0f * divisor);
int16_t r = (int16_t)roundf(0.299f * divisor);
int16_t g = (int16_t)roundf(0.587f * divisor);
int16_t b = (int16_t)roundf(0.114f * divisor);
const int16_t bgrToGray[4 * 4] = { b, 0, 0, 0,
g, 0, 0, 0,
r, 0, 0, 0,
0, 0, 0, 0 };
vImage_Error error;
error = vImageMatrixMultiply_ARGB8888(&bgraImageBuffer, &intermediateImageBuffer, bgrToGray, divisor, NULL, NULL, kvImageNoFlags);
if (error != kvImageNoError) {
NSLog(#"%s, vImage error %zd", __PRETTY_FUNCTION__, error);
}
vImage_Buffer grayscaleImageBuffer = {
.width = grayscaleFrame.width,
.height = grayscaleFrame.height,
.rowBytes = grayscaleFrame.bytesPerRow,
.data = grayscaleFrame.rawPixelData
};
void *scratchBuffer = malloc(grayscaleFrame.totalBytes);
vImage_Buffer scratchImageBuffer = {
.width = grayscaleFrame.width,
.height = grayscaleFrame.height,
.rowBytes = grayscaleFrame.bytesPerRow,
.data = scratchBuffer
};
error = vImageConvert_ARGB8888toPlanar8(&intermediateImageBuffer, &grayscaleImageBuffer, &scratchImageBuffer, &scratchImageBuffer, &scratchImageBuffer, kvImageNoFlags);
if (error != kvImageNoError) {
NSLog(#"%s, vImage error %zd", __PRETTY_FUNCTION__, error);
}
free(intermediateBuffer);
free(scratchBuffer);
}
CLPBasicVideoFrame.h - For reference
typedef struct
{
size_t width;
size_t height;
size_t bytesPerRow;
size_t totalBytes;
unsigned long pixelFormat;
void *rawPixelData;
} CLPBasicVideoFrame;
I got through the grayscale conversion, but was having trouble with the quality when I found this book on the web called Instant OpenCV for iOS. I personally picked up a copy and it has a number of gems, although the code is bit of a mess. On the bright-side it is a very reasonably priced eBook.
I'm very curious about that matrix. I toyed around with it for hours trying to figure out what the arrangement should be. I would have thought the values should be on the diagonal, but the Instant OpenCV guys put it as above.
if you need to use BGRA vide streams - you can use this excellent conversion
here
This is the function you'll need to take:
void neon_convert (uint8_t * __restrict dest, uint8_t * __restrict src, int numPixels)
{
int i;
uint8x8_t rfac = vdup_n_u8 (77);
uint8x8_t gfac = vdup_n_u8 (151);
uint8x8_t bfac = vdup_n_u8 (28);
int n = numPixels / 8;
// Convert per eight pixels
for (i=0; i < n; ++i)
{
uint16x8_t temp;
uint8x8x4_t rgb = vld4_u8 (src);
uint8x8_t result;
temp = vmull_u8 (rgb.val[0], bfac);
temp = vmlal_u8 (temp,rgb.val[1], gfac);
temp = vmlal_u8 (temp,rgb.val[2], rfac);
result = vshrn_n_u16 (temp, 8);
vst1_u8 (dest, result);
src += 8*4;
dest += 8;
}
}
more optimisations (using assembly) are in the link
(1) My experience with the iOS camera framework has been with images in the kCMPixelFormat_32BGRA format, which is compatible with the ARGB8888 family of functions. (It may be possible to use other formats as well.)
(2) The simplest way to convert from BGR to grayscale on iOS is to use vImageMatrixMultiply_ARGB8888ToPlanar8():
https://developer.apple.com/documentation/accelerate/1546979-vimagematrixmultiply_argb8888top
Here is a fairly complete example written in Swift. I'm assuming the Objective-C code would be similar.
guard let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else {
// TODO: report error
return
}
// Lock the image buffer
if (kCVReturnSuccess != CVPixelBufferLockBaseAddress(imageBuffer, CVPixelBufferLockFlags.readOnly)) {
// TODO: report error
return
}
defer {
CVPixelBufferUnlockBaseAddress(imageBuffer, CVPixelBufferLockFlags.readOnly)
}
// Create input vImage_Buffer
let baseAddress = CVPixelBufferGetBaseAddress(imageBuffer)
let width = CVPixelBufferGetWidth(imageBuffer)
let height = CVPixelBufferGetHeight(imageBuffer)
let stride = CVPixelBufferGetBytesPerRow(imageBuffer)
var inImage = vImage_Buffer(data: baseAddress, height: UInt(height), width: UInt(width), rowBytes: stride)
// Create output vImage_Buffer
let bitmap = malloc(width * height)
var outImage = vImage_Buffer(data: bitmap, height: UInt(height), width: UInt(width), rowBytes: width)
defer {
// Make sure to free unless the caller is responsible for this
free(bitmap)
}
// Arbitrary divisor to scale coefficients to integer values
let divisor: Int32 = 0x1000
let fDivisor = Float(divisor)
// Rec.709 coefficients
var coefficientsMatrix = [
Int16(0.0722 * fDivisor), // blue
Int16(0.7152 * fDivisor), // green
Int16(0.2126 * fDivisor), // red
0 // alpha
]
// Convert to greyscale
if (kvImageNoError != vImageMatrixMultiply_ARGB8888ToPlanar8(
&inImage, &outImage, &coefficientsMatrix, divisor, nil, 0, vImage_Flags(kvImageNoFlags))) {
// TODO: report error
return
}
The code above was inspired by a tutorial from Apple on grayscale conversion, which can be found at the following link. It also includes conversion to a CGImage if that is needed. Note that they assume RGB order instead of BGR, and they only provide a 3 coefficients instead of 4 (mistake?)
https://developer.apple.com/documentation/accelerate/vimage/converting_color_images_to_grayscale
I am using this SURF code to detect the logo in my image. It is working fine but it is very slow. Any idea about how can I optimize it?
- (void)findObject
{
//NSLog(#"%# %#", self, NSStringFromSelector(_cmd));
width = 0;
CvMemStorage* storage = cvCreateMemStorage(0);
static CvScalar colors[] =
{
{{0,0,255}},
{{0,128,255}},
{{0,255,255}},
{{0,255,0}},
{{255,128,0}},
{{255,255,0}},
{{255,0,0}},
{{255,0,255}},
{{255,255,255}}
};
if( !objectToFind || !image )
{
NSLog(#"Missing object or image");
return;
}
CvSize objSize = cvGetSize(objectToFind);
IplImage* object_color = cvCreateImage(objSize, 8, 3);
cvCvtColor( objectToFind, object_color, CV_GRAY2BGR );
CvSeq *objectKeypoints = 0, *objectDescriptors = 0;
CvSeq *imageKeypoints = 0, *imageDescriptors = 0;
int i;
CvSURFParams params = cvSURFParams(500, 1);
double tt = (double)cvGetTickCount();
NSLog(#"Finding object descriptors");
cvExtractSURF( objectToFind, 0, &objectKeypoints, &objectDescriptors, storage, params );
NSLog(#"Object Descriptors: %d", objectDescriptors->total);
cvExtractSURF( image, 0, &imageKeypoints, &imageDescriptors, storage, params );
NSLog(#"Image Descriptors: %d", imageDescriptors->total);
tt = (double)cvGetTickCount() - tt;
NSLog(#"Extraction time = %gms", tt/(cvGetTickFrequency()*1000.));
CvPoint src_corners[4] = {{0,0}, {objectToFind->width,0}, {objectToFind->width, objectToFind->height}, {0, objectToFind->height}};
CvPoint dst_corners[4];
CvSize size = cvSize(image->width > objectToFind->width ? image->width : objectToFind->width,
objectToFind->height+image->height);
output = cvCreateImage(size, 8, 1 );
cvSetImageROI( output, cvRect( 0, 0, objectToFind->width, objectToFind->height ) );
//cvCopy( objectToFind, output );
cvResetImageROI( output );
cvSetImageROI( output, cvRect( 0, objectToFind->height, output->width, output->height ) );
cvCopy( image, output );
cvResetImageROI( output );
NSLog(#"Locating Planar Object");
#ifdef USE_FLANN
NSLog(#"Using approximate nearest neighbor search");
#endif
if( locatePlanarObject( objectKeypoints, objectDescriptors, imageKeypoints,
imageDescriptors, src_corners, dst_corners ))
{
for( i = 0; i < 4; i++ )
{
CvPoint r1 = dst_corners[i%4];
CvPoint r2 = dst_corners[(i+1)%4];
//cvLine( output, cvPoint(r1.x, r1.y+objectToFind->height ),
//cvPoint(r2.x, r2.y+objectToFind->height ), colors[6] );
cvLine( output, cvPoint(r1.x, r1.y+objectToFind->height ),
cvPoint(r2.x, r2.y+objectToFind->height ), colors[6],4 );
//if(i==0)
width = sqrt(((r1.x-r2.x)*(r1.x-r2.x))+((r1.y-r2.y)*(r1.y-r2.y)));
}
}
vector<int> ptpairs;
NSLog(#"finding Pairs");
#ifdef USE_FLANN
flannFindPairs( objectKeypoints, objectDescriptors, imageKeypoints, imageDescriptors, ptpairs );
#else
findPairs( objectKeypoints, objectDescriptors, imageKeypoints, imageDescriptors, ptpairs );
#endif
/* for( i = 0; i < (int)ptpairs.size(); i += 2 )
{
CvSURFPoint* r1 = (CvSURFPoint*)cvGetSeqElem( objectKeypoints, ptpairs[i] );
CvSURFPoint* r2 = (CvSURFPoint*)cvGetSeqElem( imageKeypoints, ptpairs[i+1] );
cvLine( output, cvPointFrom32f(r1->pt),
cvPoint(cvRound(r2->pt.x), cvRound(r2->pt.y+objectToFind->height)), colors[8] );
}*/
float dist = 629.0/width;
[distanceLabel setText:[NSString stringWithFormat:#"%.2f",dist]];
NSLog(#"Converting Output");
UIImage *convertedOutput = [OpenCVUtilities UIImageFromGRAYIplImage:output];
NSLog(#"Opening Stuff");
[imageView setImage:convertedOutput];
cvReleaseImage(&object_color);
[activityView stopAnimating];
}
In the above code image is my original image and objectToFind is the logo which I want to detect.
Please let me know if my question is not clear.
You need to use profiling to decide which part of your code is the slowest.
Since you are using XCode, you have a built-in profiler at hands reach:
in he top-left corner you press-and-hold "Run" button and choose "Profile".
click on Profile and and select Time Profiler.
after a while you press "stop" in the profiler, and select "Hide Missing Symbols", "Hide System Libraries" and "Top Functions", deselect "Separate by Thread".
Now look up function main and there is a hidden right arrow after it. Click on that arrow and you can see time in percent and call statistics by the calltree.
This is how you start.
In general I have the following suggestions without profiling:
Avoid creating new images and memory storages as much as you can. (You can pass images for temporary use to your function, and preserve those images outside so that you can reuse them later.)
scale down your image (and your logo) to role-out major parts of the image
use less descriptors
The two rules of thumb:
you need to decide what to improve after the profiling, as profiling often yields surprising results.
The quicker part you try to improve the less potential gain you have.
So basically I was messing about with LWJGL for a while now, and I came to a sudden stop with with annoyances surrounding glReadPixels().
And why it will only read from left-bottom -> top-right.
So I am here to answer my own question since I figured all this stuff out, And I am hoping my discoveries might be of some use to someone else.
As a side-note I am using:
glOrtho(0, WIDTH, 0 , HEIGHT, 1, -1);
So here it is my screen-capture code which can be implemented in any LWJGL application C:
//=========================getScreenImage==================================//
private void screenShot(){
//Creating an rbg array of total pixels
int[] pixels = new int[WIDTH * HEIGHT];
int bindex;
// allocate space for RBG pixels
ByteBuffer fb = ByteBuffer.allocateDirect(WIDTH * HEIGHT * 3);
// grab a copy of the current frame contents as RGB
glReadPixels(0, 0, WIDTH, HEIGHT, GL_RGB, GL_UNSIGNED_BYTE, fb);
BufferedImage imageIn = new BufferedImage(WIDTH, HEIGHT,BufferedImage.TYPE_INT_RGB);
// convert RGB data in ByteBuffer to integer array
for (int i=0; i < pixels.length; i++) {
bindex = i * 3;
pixels[i] =
((fb.get(bindex) << 16)) +
((fb.get(bindex+1) << 8)) +
((fb.get(bindex+2) << 0));
}
//Allocate colored pixel to buffered Image
imageIn.setRGB(0, 0, WIDTH, HEIGHT, pixels, 0 , WIDTH);
//Creating the transformation direction (horizontal)
AffineTransform at = AffineTransform.getScaleInstance(1, -1);
at.translate(0, -imageIn.getHeight(null));
//Applying transformation
AffineTransformOp opRotated = new AffineTransformOp(at, AffineTransformOp.TYPE_BILINEAR);
BufferedImage imageOut = opRotated.filter(imageIn, null);
try {//Try to screate image, else show exception.
ImageIO.write(imageOut, format , fileLoc);
}
catch (Exception e) {
System.out.println("ScreenShot() exception: " +e);
}
}
I hope this has been useful.
For any questions or comments on the code, ask/suggest as you like. C:
Hugs,
Rose.
sorry for the late reply but this is for anybody still looking for a solution.
public static void saveScreenshot() throws Exception {
System.out.println("Saving screenshot!");
Rectangle screenRect = new Rectangle(Display.getX(), Display.getY(), Display.getWidth(), Display.getHeight());
BufferedImage capture = new Robot().createScreenCapture(screenRect);
ImageIO.write(capture, "png", new File("doc/saved/screenshot.png"));
}