RGB Mode

• three channels (Red, Green, and Blue)
• used by all monitors and on the web 
• recommended by adobe for editing color images

CYMK Mode

• four channels (Cyan, Magenta, Yellow, Black)
• used by professional printing houses.
• if you are producing a images for a publication or poster, you may need to save it in CMYK mode

Tiff

• preservation use
• large file size 
• no compression 
• can embed layers

PSD

• Photshop working file
• keeps all layers and effects 
• large file size

JPG or JPEG

• small file size
• adjustable compression 
• web and email friendly 
• widely supported 
• best for exporting with gradient 
• no transparency (use gif or png) 

Printing and publication

• Ask publisher for specific resolution and file format (TIFF is common)
• Generally 300 PPI (pixels per inch) is used for print 
• Print for a specific document size 

Save for web and devices

• GIF, PNG, JPG are common formats
• 72 PPI is standard resolution (speed is the goal) 
• In Photoshop use “Save for web” under the File menu

Save for PowerPoint/Keynote

• For image projection - you are limited to the maximum resolution of your projector. 
• 1024 pixels wide is a good size (any bigger is unnecessary and slows your presentation due to larger file size)
• Resize images in Photoshop to be the exact pixel dimension

Digital images are made up of pixels (pictures elements, one pixel=one color).  Pixel dimension describes the number of pixels in the image (width by height).  To change the resolution of an image, go to Photoshop menu --> select Image --> select Image Size.