I want to crop an image of 1176*640 to save the ROI of 1176*400 size. I am using the following snippet to acheive bit I am still getting the original image as output.
IplImage *CMyFunction::ROI(IplImage *pImage, CvRect ROI)
{
IplImage *mROI = cvCreateImage(cvGetSize(*pImage), IPL_DEPTH_8U, 1);
cvSetImageROI(pImage, rect_ROI);
cvCopy(pImage, mROI);
cvResetImageROI(pImage);
return mROI;
}
For cvCopy() the source and destination should be same size and type, that is the parameter like width, height, depth, and number of channel should be equal for both image. In your case you can change your code either like
IplImage *mROI = cvCreateImage(cvGetSize(pImage), pImage->depth, pImage->nChannels); //create dest with same size as source
cvSetImageROI(pImage, rect_ROI); //Set roi on source
cvSetImageROI(mROI, rect_ROI); //set roi on dest
cvCopy(pImage, mROI);
cvResetImageROI(pImage);
cvResetImageROI(mROI);
or
IplImage *mROI = cvCreateImage(cvSize(rect_ROI.width,rect_ROI.height), pImage->depth, pImage->nChannels); // create an image of size as rect
cvSetImageROI(pImage, rect_ROI); //set roi on source
cvCopy(pImage, mROI);
cvResetImageROI(pImage);
I understood that the pointer when leaves the function is no longer stable and declared a new IplImage* outside of the function and pass it as a parameter which proved to be efficient.
IplImage *CMyFunction::ROI(IplImage *pImage, CvRect ROI, IplImage* FinalImage)
Related
I am desperately searching for a good cropping tool. There are a bunch out there, for example:
Croppic
Cropit
Jcrop
The most important thing that I am trying to find is a cropping tool, that crops images without making the cropped image low in resolution. You can hack this by using the canvas tag by resizing the image. This way the image itself stays native, only the representation is smaller.
DarkroomJS was also something near the solution, but, unfortunately, the downloaded demo did not work. I'll try to figure out whats wrong. Does someone know some great alternatives, or how to get the cropped images in...let's say "native" resolution?
Thanks in advance!
You are relying on the cropping tool to provide an interface for the users. the problem is that the image returned is sized to the interface and not the original image. Rather than me sifting through the various API's to see if they provide some way of controlling this behaviour (I assume at least some of them would) and because it is such a simple procedure I will show how to crop the image manually.
To use JCrop as an example
Jcrop provides various events for cropstart, cropmove, cropend... You can add a listener to listen to these events and keep a copy of the current cropping interface state
var currentCrop;
jQuery('#target').on('cropstart cropmove cropend',function(e,s,crop){
currentCrop = crop;
}
I don't know where you have set the interface size and I am assuming the events return the crop details at the interface scale
var interfaceSize = { //you will have to work this out
w : ?,
h : ?.
}
Your original image
var myImage = new Image(); // Assume you know how to load
So when the crop button is clicked you can create the new image by scaling the crop details back to the original image size, creating a canvas at the cropped size, drawing the image so that the cropped area is corectly positioned and returning the canvas as is or as a new image.
// image = image to crop
// crop = the current cropping region
// interfaceSize = the size of the full image in the interface
// returns a new cropped image at full res
function myCrop(image,crop,interfaceSize){
var scaleX = image.width / interfaceSize.w; // get x scale
var scaleY = image.height / interfaceSize.h; // get y scale
// get full res crop region. rounding to pixels
var x = Math.round(crop.x * scaleX);
var y = Math.round(crop.y * scaleY);
var w = Math.round(crop.w * scaleX);
var h = Math.round(crop.h * scaleY);
// Assume crop will never pad
// create an drawable image
var croppedImage = document.createElement("canvas");
croppedImage.width = w;
croppedImage.height = h;
var ctx = croppedImage.getContext("2d");
// draw the image offset so the it is correctly cropped
ctx.drawImage(image,-x,-y);
return croppedImage
}
You then only need to call this function when the crop button is clicked
var croppedImage;
myButtonElement.onclick = function(){
if(currentCrop !== undefined){ // ensure that there is a selected crop
croppedImage = myCrop(myImage,currentCrop,interfaceSize);
}
}
You can convert the image to a dataURL for download, and upload via
imageData = croppedImage.toDataURL(mimeType,quality) // quality is optional and only for "image/jpeg" images
i am trying to do some image processing with Emgu CV.
I have raw pixel data of a gray image in an byte[]. I know the size of the image and the type.
I first create an image width the known size an type and then i want to load the date to the image (I have often done this in C++ OpenCV).
Image<Gray, Byte> image = new Image<Gray, byte>(width, height);
image.Bytes = data;
But the image is always kind of "cut through and puzzled together". It works with an image which width%4 = 0. That is why i assume it is some kind of "memory alignment" issue.
Has someone of you run into this problem and knows how to fix it?
Thanks,
Sebastian
Both your raw data and Image.Bytes are continuous pieces of memory. But every line of your array takes Width bytes, but line of Image takes Image.widthStep (I talk about IPLImage structure, don't know about Emgu pecularities) bytes, this value aligned for 4 bytes (99=>100 etc).
So you can or copy Width bytes for Yth line to Bytes[Y * widthStep] (height times), or create special 4-bytes-aligned array to collect raw data, then assign it to Image.Bytes
try using another constructor:
Image<Gray, Byte> image = new Image<Gray, byte>(width, height, bytesNum, data);
See also http://www.emgu.com/wiki/files/2.1.0.0/html/1d51c1ed-6f5e-65f9-206c-ef2d59c5c117.htm
I am getting image containing character after applying my image process. All these images (having character as content) have different size. I want to resize all images in same size without effecting it's content size. see below image:
http://techsture.com/img.jpg
I have tried some function to merge my source image with other white image but it needs both source images with same size. I need common size of images for further process.
Please guide me how can I convert my images to common size ??
Thank you
I would make a new image with the destination size, set a ROI in this new image to where you want the source image to show. Then use cvResize.
It should look something like:
int newWidth = 100;
int newHeight = 100;
CvRect rect;
IplImage* source = cvLoadImage("c:/myimage");
IplImage* dest = cvCreateImage(cvSize(newWidth,newHeight),source->depth,source->nChannels);
rect.x = newWidth/2 - source->width/2;
rect.y = newHeight/2 - source->height/2;
rect.width = source->width;
rect.height = source->height;
cvSetImageROI(dest,rect);
cvResize(source,dest);
cvResetImageROI(dest);
I have a binary file of 16 bit Intensity of the image. I have read this data in short array. And create 16 bit gray Image using the following code.
IplImage *img=cvCreateImage( cvSize( Image_width, Image_height ), IPL_DEPTH_16S, 1 );
cvSetData(img,Data, sizeof(short )*Image_width);
Where Data is short array.
Then I set ROI for this Image using this function
cvSetImageROI(img, cvRect(crop_start.x, crop_start.y, crop_width, Image_height));
and ROI is being set successfully.
Now after setting the ROI I want to access the Intensity of the Image means I want pointer of the intensity of the cropped Image. I have tried this code to access the intensity
short *crop_Imagedata=(short *)img->imageData;
But This pointer is not giving the right Intensity as I have checked that by debugging the code.
Can any body please tell me how can I get pointer of the Image Intensity.
Thanks in Advance
Hello I have tryed the following to find what maybe you wannt to do:
IplImage *img=cvCreateImage( cvSize( 15, 15 ), IPL_DEPTH_16S, 1 );
cvSet(img,cvScalar(15));//sets all values to 15
cvSetImageROI(img, cvRect(4, 0, 10, 15));
short *crop_Imagedata=(short *)img->imageData;
((*crop_Imagedata) == 15) // true
The value that you will get is not in the roi! imageData of the IplImage structure is just a simple pointer and not a function !!! the rois of opencv is something that isn t that well documented and easy to use in my opinion. Maybe all algorithms of opencv use the rois somehow. I use them to but there is no such automatic function with the standard iplimage structure to simple use them.
If you wannt more magic try to use the new cv::Mat object...
but if you still wann t to use rois then you will have to allways to use
CvRect roi = cvGetImageROI(img);
method to check all the time the position. After that you will have to add the roi offset:
((short*)(img->imageData + (roi.y+ypos)*img-widthStep))[roi.x+xpos]
remember the standard Opencv is a C library not a C++ ! btw when mixing cv::Mat rois can be a bit annoying to. To copy an iplimage to a cv::Mat without roi I have to do the following:
CvRect roitmp = cvGetImageROI(ilimage);
cvResetImageROI(ilimage);
cv::Mat tmp = cv::Mat(ilimage).clone();
cvSetImageROI(ilimage,roitmp);
maybe here someone knows the right way of working with rois...
I am creating a brush using CreatePatternBrush with a bitmap created with CreateBitmap.
The bitmap is 1 pixel wide and 24 pixels tall, I have the RGB value for each pixel, so I create an array of rgbquads and pass that to CreateBitmap.
This works fine when the screen color depth is 32bpp, since the bitmap I create is also 32bpp.
When the screen color depth is not 32bpp, this fails, and I understand why it does, since I should be creating a compatible bitmap instead.
It seems I should use CreateCompatibleBitmap instead, but how do I put the pixel data I have into that bitmap?
I have also read about CreateDIBPatternBrushPt, CreateDIBitmap, CreateDIBSection, etc.
I don´t understand what is a DIBSection, and find the subject generally confusing.
I do understand that I need a bitmap with the same color depth as the screen, but how do I create it having only the 32bpp pixel data?
You could create a DIB because you can use a Device Independent Bitmap independently of the screen color depth. See CreateDIBSection().
How can you create it having only the 32bpp pixel data? A DIB can be created with 32bpp data. As you can read in the documentation:
The CreateDIBSection function creates
a DIB that applications can write to
directly. The function gives you a
pointer to the location of the bitmap
bit values.
If hSection is NULL, the system
allocates memory for the DIB. If the
function succeeds, the return value is
a handle to the newly created DIB, and
*ppvBits points to the bitmap bit values.
Try something like this:
VOID *ppvBits = NULL;
BITMAPINFO BitmapInfo;
memset(&BitmapInfo, 0, sizeof(BITMAPINFOHEADER));
BitmapInfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
BitmapInfo.bmiHeader.biWidth = 1;
BitmapInfo.bmiHeader.biHeight = 24;
BitmapInfo.bmiHeader.biPlanes = 1;
BitmapInfo.bmiHeader.biBitCount = 32;
BitmapInfo.bmiHeader.biCompression = BI_RGB;
HBITMAP hBitmap = CreateDIBSection(hDC, &BitmapInfo, DIB_RGB_COLORS, &ppvBits, NULL, 0);
In our case *ppvBits points to 1 * 24 * (32 / 8) allocated bytes.
It is important to know that if biHeight is positive, the bitmap is a bottom-up DIB and its origin is the lower-left corner. See BITMAPINFOHEADER Structure for more info.
I solved it by using CreateCompatibleBitmap and SetPixel. Not the best option I guess, but it works.