Fastest Algorithm to scale down 32Bit RGB IMAGE

algorithmimage-processingimage-scaling

which algorithm to use to scale down 32Bit RGB IMAGE to custom resolution? Algorithm should average pixels.

for example If I have 100×100 image and I want new Image of size 20×50. Avg of first five pixels of first source row will give first pixel of dest, And avg of first two pixels of first source column will give first dest column pixel.

Currently what I do is first scale down in X resolution, and after that I scale down in Y resolution. I need one temp buffer in this method.

Is there any optimized method that you know?

Best Solution

The term you are looking for is "Resampling." In your case you want image resampling. You seem to already be doing linear interpolation, which should be the fastest. Here are ~6 base algorithms. If you really want to delve into the subject look into "resampling kernels."