When I first started playing photography properly I was content to use iPhoto to do my basic post-processing. Now I'm in a mac-less environment and I like to use GIMP to edit things. Unfortunately I wasn't really sure what iPhoto was doing with my photo: I would just tweak the sliders until I was happy. That left me wondering what the "real" edit is to achieve the effect of the "Shadows" and "Highlights" sliders.
Answer: It's all in the levels editor. Go to "Levels..." in the Colors menu and you're greeted with a level-editing histogram.
- Moving the middle triangle in Input Levels to the left is the same as increasing the "Shadows" slider in iPhoto.
- Moving the right triangle in Output Levels to the left is the same as increasing the "Highlights" slider in iPhoto.
And with a bit of tinkering you can work out how to do other things too. Hooray.
One Comment
Not quite. Moving the triangles in Gimp is the same as moving triangles in iPhoto (they really do exist!).
The highlights/shadows thing is actually a curves adjustment (look it up); moving the left (dark) end of the curve is shadows, the right (bright) end of the curve is highlights. It's more difficult to get right, but gives a lot more control.