Let me start off by stating I use PhotoShop CS2.
If any others who use different programs would like to add how it's done with that program could help others lots.
Batch processing makes changing loads of images the same way easy. Whether it's 10-100, or in DDO's case 1200+
You only need to change 1 image in the folder with all your images and then process them and they will all change to how you did it.
Screenshots will follow each step when I get some time.
1. Open Photoshop
2. Choose an image from the folder of items you wish to change and open it in Photoshop.
3. Go into Windows -->Action or Alt+F9
4. Choose to create a new action. If you don't know which one, screenshot will follow or hover over them near bottom.
5. Name the new action, something u will remember, then hit Record.
6. Now the fun part. Do whatever changes you want to the image you opened. Whether you are simply changing the hue/saturation to change it colors...or using filters to blur it, shade it, etc.....
Note: Whatever you do to this image is being recorded and when done, the same changes you made will be made to all 1200+ images.
7. When you are done, choose to STOP recording by hitting the bottom left stop button in the action window.
8. Go to File -->Automate -->Batch.
This opens a new popup, simply choose the Folder you wish to change. Then choose the Action you wish to use...most likely the one you just created.
Choose where you want to save the images being changed, whether you want to overwrite the current folder or have it create a new one.
9. Choose OK when done, and let photoshop do its work.
When done, all images will be changed to how you did it.
Hope it helps, and as stated before will add screenshots later to the steps that they might actually be needed on.