image-manipulation

Is there a faster way to rotate a large bitmap by 90 or 270 degrees than simply doing a nested loop with inverted coordinates? The bitmaps are 8bpp and typically 2048*2400*8bpp Currently I do this by simply copying with argument inversion, roughly (pseudo code: for x = 0 to 2048-1 for y = 0 to 2048-1 dest[x][y]=src[y][x]; (In reality I do it with pointers, for a bit more speed, but that is roughly the same magnitude) GDI is quite slow with large images, and GPU load/store times for textures (GF7 cards) are in the same magnitude as the current CPU time. Any tips, pointers? An in-place algorithm

I've recently come across a problem which requires at least a basic degree of image processing, can I do this in Python, and if so, with what? The best-known library is PIL . However if you are simply doing basic manipulation, you are probably better off with the Python bindings for ImageMagick , which will be a good deal more efficient than writing the transforms in Python. Depending on what you mean by "image processing", a better choice might be in the numpy based libraries: mahotas , scikits.image , or scipy.ndimage . All of these work based on numpy arrays, so you can mix and match

I want to read an image into MATLAB, draw a rectangle on it, and then save the image. Also, I'm just learning MATLAB--please be gentle. It seems like it should be simple, but I can't seem to do it. im = imread('image.tif'); imshow(im); rectangle('Position', [100, 100, 10, 10]); imwrite(im, 'image2.tif'); Even though I can see the rectangle on the image, the saved image does not display the rectangle. How can I save the image and have the rectangle show up? FWIW, I've already tried saveas() , but that gives me a HUGE image. Is there a way to use saveas() and make the saved image the correct

I try to erase parts of a bitmap in my Android application by using Porter-Duff Xfermodes. I have a green background which is overlayed by a blue bitmap. When I touch the screen a "hole" in the overlaying bitmap is supposed to be created making the green background visible. Instead of a hole my current code produces a black dot. Below is my code. Any ideas, what I am doing wrong here? /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,

So I ran across this recently: http://www.nicalis.com/index.php And I was curious: Is there a way to do this sort of thing with smaller images? I mean, it's pixel art, and rather than using an image with each pixel quadrupled in size couldn't we stretch them with the code? So I started trying to make it happen. I tried CSS, Javascript, and even HTML, none of which worked. They all blur up really badly (like this: http://jsfiddle.net/nUVJt/2/ ), which brings me to my question: Can you stretch an image in-browser without any antialiasing? I'm open to any suggestions, whether it's using a canvas,