What does the Photoshop "Equalize" command actually do?

[ChadPT18]

Image > Adjustments > Equalize (At the bottom of the menu)

Was just wondering what this command actually does when you apply it to an image.

I can see it's changing the light and/or colour but technically what is going on?

Thanks in advance!

- CT

[davescm · Accepted solution]

Hi

I rarely (read never) use this so had to look it up.

It looks across the channels for the darkest pixel in any channel and maps that to 0 (shifting the other 2 channels (if RGB) proportionally. Similarly it looks for the lightest pixel in any channel and maps that channel value to 255 ( again shifting the other 2 channels proportionally.  All other pixels are then shifted proportionally, effectively increasing the contrast.

My recommendation would be - forget it and use the much more controllable (and non-destructive) curves adjustment layer.

Dave

[dough63376286]

I use equalise quite a bit, sometimes it works wonders sometimes it doesn't, more often than not it's great.
Duplicate the background then equalise, play around with % and mode. It can put a lot of detail back in a bright sky or the shadows. You can mask it or just elete if you don't like the effect.

I find it very useful and far simpler to use than shadows / highlights.

[TangCanada]

Another useless command... just like the paint bucket tool.