http://www.opensword.org/Pixen/
Features
Pixen implements all of the usual graphics-program features: a variety of selection tools; the useful shape tools; the eye-dropper; the pencil and eraser; the ablity to read and write from many formats; a full implementation of layers, including independent opacity controls, merging, and reordering; and a variety of other features, including an auto-save to help recover from crashes.
However, what differentiates Pixen from other graphics programs, besides the grace with which the aforementioned features were implemented, are the new features unique to Pixen.
Custom Backgrounds
Pixen has a custom backgrounds configurator in which one can configure how the canvas looks where the image drawn on it is transparent. The built-in backgrounds include slashed-lines, checkered-squares, flat-color, and custom-image. Adding a new background type is as simple as dragging it into ~/Library/Application Support/Pixen/Backgrounds/Presets/. It’s also possible to include third-party background types. For information on programming a new kind of background, please talk to us.
This is exceedingly useful, but Open Sword Group takes the feature one step further: One has the option to choose two backgrounds. One of these is used when the mouse is inside the image; the other when the mouse is outside.
If one is drawing a sprite, for instance, one can specify an image of a grass tile to be used as the alternate background (and a plain checkered background to be used as the main one). Simply by moving one’s mouse outside the image, one can see how the sprite looks on a grass tile. Moving the mouse back in will change the background back and resume normal operation. And of course, Pixen saves the background configuration with the document so one can keep sane with thousands of sprites.
“Smart” Palettes
Another unique feature of Pixen is the “smart” palette. It is a common problem for all artists, but for pixel artists especially, to have finished a part of a work but to be dissatisfied with the color choices. Other programs would force the user to painstakingly use the fill-bucket with the new color in every place the old color inhabited, which is tedious and error-prone.
In Pixen, however, with the Smart Palette enabled, one can simply double-click the offending color in the palette and change it to whatever one wishes. If the reddish hue of the character’s cape displeases the artist, he can easily change it to something black or something pink. It is an incredible freedom and convenience.
Pixen also makes it easy to perform “palette swaps”, the replacement of each color in the original image with a corresponding new color. This technique was pioneered in the days of the Atari and NES, and will, besides being useful for prototyping numerous different colorations of a sprite, will remind many users of those now-ancient RPGs that only recolored enemies to indicate increased toughness.
To select the color for the left-click tool in the palette, left-click the color in the palette; to select the color for the right-click tool, right-click the color in the palette.
Advanced Grid Customization
Pixen has an optional 1px by 1px grid overlay like many other art programs. The distinguishing aspect of Pixen’s grid is its configurability: everything from the color of the grid lines to the width and height of the grid rectangles is user-configurable and saved in the current document. This is extremely usefu for sprite sheets, and many other applications of pixel art.
Tiled View
The grass tile is many pixel artists’ first step. It is also one of the hardest things to really get right. To help artists avoid the cheapness and ‘griddiness’ of poorly-tiling tiles, Pixen offers a tiled editor and view. When active, the tile is shown surrounded by itself. Any of these images is editable, and one can draw across borders freely.
This is a complex feature, and difficult to implement speedily, so at present it is best used to clean up tiles that don’t seem ‘quite right’ and not to fully create new ones from scratch, necessarily. It is best to work with it and see what is right for oneself; we do believe that this tiled view is an incredibly useful feature, though, and encourage its use as much as makes sense.
Alignment Crosshair
Many pixel artists find themselves drawing guides on the edges of their images or have difficulty lining up pixels properly, or keeping symmetry where it is necessary. Pixen’s alignment crosshair feature is simple to turn on, configurable in color, and will show one exactly where the incoming pixel is to be placed.
Right-Click Tools
Pixen’s hotkeys offer a convenient and customizable way to change tools, but moving one’s hand to the keyboard and back can slow down an artist. Therefore, Pixen offers another palette of tools (reached by ‘unfolding’ the main palette) to be used with the right mouse button (or control-click). The right-click tools are identical in functionality and features to the left-click tools.
Aqua-Compliant
Unlike every other graphics program for Mac OS X, Pixen features a fully Aqua-HIG-Compliant user interface, with no special hacks, no proprietary panels, and nothing ‘weird’ or unexpected. Pixen is written fully in Cocoa, exclusively for Mac OS X, and therefore blends seamlessly with the rest of the system.