Question

ello,

I am looking for the most efficient way to do the following:

Take an input image in bitmap form, inputIMG. Map each pixel from the
input image, inputIMG(x,y), to a new value using a lookup table,
lookupTable, which is basically an 256×3 element array.

If the input pixel is valued at RGB [192,123,154] the output pixel
value would be the value at lookupTable(192,123,154).

I can easily code this going through the input bitmap pixel by pixel using Bitmap.setPixel(), but there would likely be a lot of overhead associated with that approach due to many repeated calls and I was wondering if there was a more efficient way to do it?

Thanks in advance.

Answer 1

If you don’t want to set each pixel individually you have two options.

One is to set patches of pixels at the same time with setPixels(int[], int, int, int, int, int, int):

The other is to create a new bitmap using an array of colors: createBitmap(int[] colors, int offset, int stride, int width, int height, Bitmap.Config config)

Both methods are explained in the Android Bitmap docs