Seashore is an open source image editor for Mac OS. It features gradients, textures and anti-aliasing for both text and brush strokes. It supports multiple layers and alpha channel editing. It is based around the GIMPs technology and uses the same native file format.
However, unlike the GIMP, Seashore only aims to serve the basic image editing needs of most computer users, not to provide a replacement for professional image editing products. More Info »
Features
Full support for the XCF file format
Reading and writing TIFF, PNG, JPEG and JPEG 2000 file formats
Reading BMP, GIF, PDF, PICT, and XBM file formats
Layers and layer merging effects
Individual editing of layer channels
Transparency effects and transparency in gradients
Arbitrary selection regions (i.e. through a lasso tool)
Anti-aliased paint brushes
6 gradient effects
Graphics tablet support
Plug-in filter effects