CORRECTING UNDER-EXPOSURE - Using Curves to ad density.
Back to main Photoshop page
All images © by Jon Davison 2007.

Prior to Photoshop there was not much chance of salvaging an under-exposed
colour slide like this. Now with Photoshop, we can make adjustments and
pretty much rectify this problem if shot digitally. For instance this shot of
the house in Western Australia is so under-exposed, that I would have
ditched this a few years ago.


Original frame

1. Lets start the process. Open the 35cm work file by clicking here.

2. We should try Auto-Levels just to see if anything happens. It is always worth trying
this with any image, you may find colour casts etc that are not obvious at first.


3. Okay, so it offers a bit of density. Just go 'Co-Z' to undo this move and go back to
the start.

4. Now go 'Image-Adjustments-Curves' This will give you a diagonal line going bottom left to
top right. Clicking and moving this line from its centre changes the overall density of the
image. A point made between the middleand the bottom, changes the shadow density.
A point made between the middle and the top, changes the highlight denisty. So...



So simply by adjusting the Curves in an image, we can bring back information that
appeared to be non-existant.

The final thing we will do is adjust the individual colours, to enhance or reduce the
colouration, as the Curves have added contrast to the colours by saturating them.

5. 'Image-Adjustments-Selective Colour'. This brings up a comprehensive menu with
4 attributes to each colour.



6. Lets start with Yellows. Here we make changes by taking away a colours opposite.
In this case we need to remove a small degree of Blue, which is a mixture of Cyan and
Magenta. Next we do the same with the Blue by adding a bit of yellow. Note how
unreal the sky looks, okay it can look like that but the yellow just adds a touch of
realism to the composition.





The final image with density adjusted, and Selective Colours balanced just a tad.
Note how the yellow in the blue, and the removal of Megenta in the grass has given a
more realistic rendering. Click for a larger view.

Good luck!
Jon