>>3792440(pic related is a example for a not so good picture. the skin tone in the rgb channels is more or less the same level. which indicates a too bright skin and a too blue tone. in the saturation channel you can see that the skin is hardly saturated. which means the skin is not only too bright but also not saturated enough (which is most likely because it would be too blue). also the saturation channel shows some weird artefacts, the halo around the person, which must be some internal unsharp mask or the like. also the contrast in the saturation channel is too low, which means that dark and light areas are saturated. bad thing. means you should def. only sharpen on the luma channel. the hue channel is a mess. big blant clusters. that's most likely some compression loss. so there is not much playroom for color correction. the a and b channels are very soft and have a bit too much contrast. this means again that the color information is fucked up and sharpness is only achieved by the luma channel.
the picture is more or less not possible to rescue. one could lower gamma in blue a bit, saturate yellows a bit, sharp lightness a little and equalize saturation in highs and shadows a bit. but this might even make things worse. in this case, I just would let the image how it is. no job able to do.)
