You can get to these settings by going to Core > Settings > Application Style Settings > Logos and Seals.
They must have a filetype of .jpg or .png, saved for the web. Jpg files will give you a better image quality.
PNG files must be saved as PNG-8 with no transparency or you will have undesired results.
If you are creating a watermark, you can adjust the opacity of the logo in Photoshop, but just make sure to have a white background instead of transparent.
It's also important to use the correct dimensions so the image is not squished or stretched.
The best way to save a logo or seal is to use the following settings in Photoshop:
- For logos: Create a document that is 400 x 200 px (72 dpi).
For seals: Create a document that is 800 x 800 px (72 dpi).
- Bring your logo or seal into this document and make sure to size it proportionally by holding the Shift key while resizing.
- Be sure there is a white background if your logo has any transparent areas. (Make a new layer below it and make it white).
- Click File > Save for Web...
- Under presets on the right, choose PNG-8.
Note: If your logo has a slightly tinted white background on the actual report card, try setting the Web Snap setting in this Save for Web dialog box to about 30% or higher and re-save the image.