Should I perform the final color space conversion before or after final sharpening of an image?

Question

When preparing an image for the web (or other media), the last two steps is usually to resize the image to the desired resolution and sharpen it at that resolution. However, when working in a larger/different color space than the final result is going to be exported in, when should I convert to the target color space relative to these two operations?

Answer

My last steps, in order, are resize, sharpen, convert color space from ProRGB to sRGB, convert to 8-bit.

The only really critical orders are sharpening after resizing and changing to 8-bit after changing the color space.

In fact, I was curious, so I just tried. One copy, I did my above steps. On the other copy, I converted color space, converted to 8-bit and then resized and sharpend. I put the images over each other and changed the blending mode to difference.

There was absolutely no pixel level difference between the two. I expect to see a few minor differences at 100% that would never show up on the print, but in the case of this one particular photo, there were absolutely no differences at all.

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