FlySketch Graphic Compositing Modes
If you are running FlySketch 1.5 on Mac OS X 10.4 or later, you will notice an extra pallet with various “Compositing modes”. What the heck are those?
Well, direct from Apple, here’s what you get:
- Clear
Transparent.
- Copy
Source image.
- Destination Atop
Destination image wherever both images are opaque, source image wherever source image is opaque but destination image is transparent, and transparent elsewhere.
- Destination In
Destination image wherever both images are opaque, and transparent elsewhere.
- Destination Out
Destination image wherever destination image is opaque but source image is transparent, and transparent elsewhere.
- Destination Over
Destination image wherever destination image is opaque, and source image elsewhere.
- Plus Darker
Sum of source and destination images, with color values approaching 0 as a limit.
- Plus Lighter
Sum of source and destination images, with color values approaching 1 as a limit.
- Source Atop
Source image wherever both images are opaque, destination image wherever destination image is opaque but source image is transparent, and transparent elsewhere.
- Source In
Source image wherever both images are opaque, and transparent elsewhere.
- Source Out
Source image wherever source image is opaque but destination image is transparent, and transparent elsewhere.
- Source Over
Source image wherever source image is opaque, and destination image elsewhere.
- XOR
Exclusive OR of source and destination images. Works only with black and white images and is not recommended for color contexts.
Shamelessly stolen from: http://developer.apple.com/documentation/Cocoa/Reference/ApplicationKit/ObjC_classic/Classes/NSImage.html