Exposure Correction

[EdwardA]

Hi,

i have been trying to follow Katrin Eastman's example of appling a negative mask to correct an under exposed picture.

Everytime I try instead of having a BLACK channel in the load selection (figure 3.35 page 61) I have a GRAY channel.

My test have never turned out correctly. Do I have some default wrong in Photoshop? I have tried with a background layer and changing the background to laye 0. With layer 0, I get a transparency channel (I think).

Any tips would be appricated.

Edward

[Flora]

Hi Edward!

Welcome to RP!

...I've been reading Katrin Eismann's book like a bible for the last two years ... and never noticed that 'black' channel before you pointed it out! ... I definitely need glasses ...

Even though she writes that she concentrates on Version 6 of Photoshop, she might have prepared this particular example with a previous version, because, since I've been using Photoshop, I've always had a GRAY channel as well ... and it always worked perfectly ...

It shouldn't be necessary to change the background at all .... Sometimes I had similar problems to yours until I realized that I'd left out one 'step' or misread it ... so, starting from scratch and carefully following step by step I usually managed to get the results I was expecting...

[EdwardA]

Exposure Correction

Thank you for the quick response.

I have tried several times to get this to work and again my first attempt tonight did not. The first image is of a granite marker and maybe not having enough contrast was giving me the problem.

I tried another it worked out a lot better. Thank you for the infor about gray in the fillbox I though all along that was the problem.

I hope I attach this right.

Thanks again
Edward A.

[Flora]

You are welcome, Edward

....and you did quite a good job with that picture!

You can 'uncover' details from the shadow in a picture only if those details are there to start with..Sometimes, after lifting the shadows, you only find a plain gray 'blob' of colour... In this case, there isn't much you can do beside 'borrowing' details from a similar picture.

Sometimes, the 'Fill-Flash' technique (that's how this exposure correction is called) alone is not enough to completely lift the shadows in a picture ... In this case, you might try to repeat the procedure or, if that's not working for you, you can try to correct even further by using other Tools on top of it: Curves, Levels, Brightness&Contrast etc. like I did in the attachment.

If you can, you might post your 'granite marker' picture .... You might be surprised at the results you may get...

[VG-vizualgroove]

Simple technique to start with...

Edward,
Open your image in PS
Press Ctrl-J
Set layer blending mode to screen
Copy this new layer again using Ctrl-J as many time as is necessary to bring out the shadow details

This method will quickly let you see what is in the shadow areas of an underexposed image and then determine if you have to do any noise adjustments before you start working on bringing out detail.
Most people make the mistake of bringing up the shadows first. Also, just go to Select-Color Range and then select the shadows color range from the drop down. You can combine the selection with the screen layer above.
HTH,
VG