When adding a part of one image onto another, the biggest problem is often the mismatched lighting which means the added part doesn't blend and so looks obvious. There is a little known tool that is often over-looked by photo editors but which can be extremely useful so I thought I'd do a little tutorial in the hope it might help someone.
Example:
As an example, I have a picture of Horton Tower in Dorset which was taken in the 'golden period' as the sun was going down and which gives the building a lovely warm feel. Although the sky is still blue, the clouds are off-white, more yellowish:
Now, I have decided to add a seagull flying in the empty space top left. I have one in another image but it was taken in the middle of the day so has a more blue tone to it. I have used the extract tool to make it into a selection that I can move across into the other image:
The problem comes when we move this across to the source image (The tower):
Look at the bird and you can see that the tone is not right for the image, it just doesn't blend properly so we need to make changes before we can use the seagull in this image and make it look believable.
Curves Tool:
Most people know about the Curves Tool (Ctrl+M) which allows us to adjust the lighting and contrast. We are going to open this tool but not adjust the line itself.
First let's make sure we are ready so have BOTH pictures open, the one you are taking from and the one you are adding to. Make certain these are laid on your screen so that you can see both pictures fully. Now select the picture you are taking from (in the case the Seagull). Open the Curves tool but don't adjust anything, just click on the OPTIONS button. This in turn opens another window called the 'Auto Color Correction Options' as in this picture:
Ok, take a look at this window and select 'Find dark and light colors'. Uncheck the box underneath (if it is checked).
Now in turn we are going to select the dark, mid and light tones but we take these from the target image (The tower) and not from the seagull image. You can see from the following image where I took the tones from:
The shadow tone is easy enough, just select the darkest area on the target image. The highlight area also is pretty obvious but you can often find the best choice is not actually the absolute brightest point so feel free to try a few areas. This is much more so when you choice the midtone. Remember we are looking to apply the colouration of the target image so don't just look for a mid-gray, instead look for a middle orange tone to get a warmth into our seagull. The seagull image will change in real time so you can see what effect you are having. Experiment until you feel the seagull has a tone that looks similar to the tone of the target image.
IMPORTANT:
When you go to close the Options and Curves windows, you will get a question window pop up asking whether to save the new target colours as defaults:
SAY NO! If you say yes it will use these tones the next time you come to play with a normal image and you'll be confused as to why it is doing strange things!
Final result:
If we look in close up, this is what our seagull now looks like:
This is not where I want the bird to be though, it's a bit big and might frighten people as well as make a real mess of any nearby windscreens! So I have resized, rotated slightly and put it into a believable position. At the end of the day, this is just a play, not an image I intend to use. But you can see the difference the tonal changes have made to making the bird blend properly into the image:
So that's all there is to it. Please give it a try and if you find it useful, let me know. I do hope it helps.
Cheers,
Rob