Effect of colour space on file size

[David Hughes]

This is sort of colour management.....

I discovered that exporting jpgs out of Lightroom gives very different file sizes if I set the colour space to Adobe RGB (e.g. 348k) than if I set it to sRGB (1.7MB). Can anyone explain why this would be the case ?

Dave

[David Hughes]

Forget this - user error.

I had been using a USM action in PS after exporting from LR and resaving to jpg. I had changed the quality setting for jpg in PS and not changed it back (and the USM action doesn't hold the JPG settings). At the same time I changed the colour space and hence assumed that was the problem.

Time to go back to bed I think.....