How To Read RBG-Pixel values from CGImage in ios

Question

How I can Read the RGB-Pixel by Pixel values from CGImagea also after how to assign it to UIImage

score 0 · Answer 1 · answered Jun 21 '12 at 06:26

0

according this link Bitmap is used to work with images defined by pixel data.

yourimage= new Bitmap(@"image address", true);

    int x, y;

    // Loop through the images
    for(x=0; x<yourimage.Width; x++)
    {
        for(y=0; y<yourimage.Height; y++)
        {
            //Get Pixel Color
            Color pixelColor = image1.GetPixel(x, y);
            Color yourColor = Color.FromArgb(pixelColor.R, 0, 0);
            //Set Pixel Color
            yourimage.SetPixel(x, y, yourColor );

answered Jun 21 '12 at 06:26

KF2

9,887
8
44
77

your right but i want solution for monotouch I knw c# support Bitmap class but this class has no support in monotouch – Jun 21 '12 at 12:18
Not sure if at the point of the above comment MT didn't support Bitmap class, but this solution now works almost flawlessly. The only thing different is `yourimage = new Bitmap(myUIImage);` – Brad Moore Jan 05 '13 at 04:58
Not sure what the deal is with my above comment, but it appears that Bitmap class no longer exists for MT. – Brad Moore Aug 20 '14 at 23:33

score 0 · Accepted Answer · edited May 23 '17 at 11:50

To read RGB pixel values with MonoTouch you can use the code posted in the answer to the following post (works fine for me):

Retrieving a pixel alpha value for a UIImage (MonoTouch)

You can also find the following post useful:

Transparent PNGs in Monotouch for iOS

And here is a link to a working implementation of mine of a convolution filter, that reads and demultiplies the pixel's rgb values (on iOS all images with alpha channel are stored in a premultiplied-alpha format):

How to Optimize this Image convolution filter Method in MonoTouch?

Remember that reading pixel values is very slow, even if you use the trick to create a bitmap context of only 1x1 pixels.

How To Read RBG-Pixel values from CGImage in ios

2 Answers2

Linked