Bitmap Colors & Editing in CMYK

Question

I have a Xamarin.Android app with an Android.Graphics.Bitmap for which I need to view each pixel's color in CMYK (as opposed to RGB). I also need to be able to rotate & crop the Bitmap. I am not extremely familiar with working with graphics & images, and could not seem to find good ways to do these things. Any ideas?

Answer 1

Hello,

I need to view each pixel's color in CMYK (as opposed to RGB)

If you can get the RGB data, you can convert it to CMYK color,

double R = R / 255
double G = G / 255
double B = B / 255

double K = 1 - Math.Max(R, Math.Max(G, B));
double C = (1 - R - K) / (1 - K)
double M = (1 - G - K) / (1 - K)
double Y = (1 - B - K) / (1 - K)

I also need to be able to rotate & crop the Bitmap.

For crop the Bitmap, you can ceate a new bitmap , set start cropped postion in X, Y axis and cropped bitmap's width and height.

 public Bitmap CropImage(Bitmap bitmap,int x, int y ,int width, int height)
        {
            Android.Graphics.Bitmap crop = Android.Graphics.Bitmap.CreateBitmap(bitmap, x, y, width, height);
            return crop;
        }

For rotate the bitmap. You can use Matrix to achieve.

        public Bitmap RotateImage(Bitmap image, int width, int height)
        {
            var matrix = new Matrix();
            matrix.PostRotate(90);
            return Bitmap.CreateBitmap(image, 0, 0, image.Width, image.Height, matrix, true);
        }

As note:Avoid duplicate questions

Best Regards,

Leon Lu

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