making the assumption that this is working from a source image, i would start off by defining a pseudo raster of rectangles to cover the image and sample the image into the pixelly psuedo raster. next, for each individual rectangle i would quantize the sampled hue coarsely into like 16 steps and then set up a little gradient in saturation and brightness (or possibly just saturation?) going from left to right and add some controls to this so i could tweak the gradient ranges till it looked juicy
fake code
int cellSize;
for(i<width, i+=cellSize){
for(j<height, j+=cellSize){
sampleColor=grab from image at (i,j)
outColor.hue=sampleColor.hue/16;
for(k<cellSize,k++){
outColor.Saturation=gradientWeightS * k;
outColor.Bright=gradientWeightB * k;
draw a pixel with outColor at (i+k,j)
}
}
}