There are a few dedicated bitmap editors out there with features specific to pixel art and sprite animation. One that I like is Pickle. It features a stripped down feature set designed to give the pixel artist just the tools that they need to use.
A full featured image editor like Photoshop or Gimp can just get in the way of the pixel artist, providing too many tools with too many options, most of which are highly un-optimal in their standard configuration for pixel art techniques. By stripping the unnecessary, Pickle gives the user a streamlined interface that they can learn quickly and use very quickly once they’ve learned the handful of keyboard shortcuts to enable them to switch between tools and modes with great efficiency.
I first tried Pickle sometime in the last year, and since then a new version has come out. While I didn’t quite grok the beauty of the interface at the time, I’ve become more experienced with pixel art since then, and decided to give it another try.
Pickle is available now only a paid license, no longer a nagware/donationware license. There is a 7-day trial mode, but after that you have to pay to use it.
If it’s the sort of tool you’ll get a lot of use out of, it’s probably worth the price.
For serious sprite animation, I’d recommend Spriter, which is still in beta, but has been coming along nicely in recent releases. But to create the sub-sprite bitmap resources that you’ll import into Spriter, Pickle is still a good tool to consider, especially if your art style is pixel art and you don’t do a lot of work with gradients and filters and the like.
For simpler sprite animations, Pickle has an onion skin feature that shows the previous and next frames in an animation loop so that you can compare the frame you’re working on against them. I find this really speeds up the process of creating simple animations, and removes a lot of the guesswork and trial and error. While it doesn’t have as many features as the built-in Sprite Editor that comes with GameMaker, it makes up for this by providing a well-thought out interface for the tools it does give you, and providing only what is essential to producing pixel art.
Couldn’t be easier, really. The manual is simple and fits on a single page on the web site, which covers the entire application from start to finish.
All a pixel artist really needs is the pencil, paintbucket, eraser, and selection tools. When you’re manipulating a bitmap at that level, you really don’t need any other tools. Line and shape tools might be useful, but aren’t really necessary, particularly for smaller sprite and tile bitmaps. A text tool would be nice as well, in a more featureful app, but again, for the intended purpose of creating tiles and sprites, not needed.
Pickle shows its strengths in two areas: Tile making, and animation.
For tile making, it provides a means to shift the bitmap so you can more easily discern hard edge transitions in order to smooth them out. There are also mirroring modes which allow you to make symmetrical shapes easily, by mirroring the pixels horizontally, vertically, or both, as you draw them.
For animation, I really like its “onion skin” feature, which overlays the previous and next steps in the animation as a translucent layer, which you can use to guide where you draw the current frame. This helps you make better, smoother animations in less time because you don’t have to flip back and forth between frames for comparison and preview it constantly to make sure it’s right.
You can only save up to 10 color palettes. This seems arbitrary and way too small. I’d like to be able to develop a palette for any particular project I happen to be working on. 10 is way too small and there’s really no excuse for it to be so low a number. I should be able to browse a directory full of xml files that define custom palettes, however many I need. Pickle does come with a few built-in color palettes that are useful for game development: the GameBoy an Atari palettes are most welcome, but they should keep adding more: NES and Commodore 64 perhaps being the most necessary. In time, I’d like to see every classic console palette emulated.
I also found the palette to be very tiny and hard to click on, and wished that it was quite a bit larger.
There’s a lot in this section, but don’t let that mislead you into thinking that I don’t like Pickle as-is. Rather, I’m so enthusiastic about it that I can’t stop thinking of ways that I’d improve it if I could. I forwarded these suggestions to their feedback email, so I’ll be thrilled if the developer decides to incorporate any of these ideas.
Altogether, I admire the minimalism of the Pickle interface and the easy learning curve that the constrained interface permits. I wouldn’t like it to lose that beauty by adding too many new features, but I feel that if the following ideas were incorporated into the interface, it would make for just about the perfect pixel art image editor.
Indexed color/Palette swapping. Switching to a different color palette from the selection of saved palettes doesn’t cause the colors in an image you’re currently editing to change. This might be a desired capability, however. Old game consoles used indexed color and palette swaps to good effect, and an easy way to replicate this in Pickle would be awesome. An “indexed color mode” which changes the colors in the current image when a new palette is selected, instantly re-coloring the image with the new palette, would be a great feature.
Easier palette building. It would also be nice if I could define a new custom palette based off of an existing palette (such as “night colors from the NES palette” for example) — by dragging a color swatch (or a range of swatches) from one palette onto a new palette.
Color switching shortcut. A keyboard shortcut to cycle through the colors in the palette to enable rapid switching would be useful. There is a shortcut (x) to switch between the primary and secondary colors, and that is OK for what it is. But when I have a lot of colors in the palette, I want to be able to switch between any of them easily, maybe though CMD+arrow keys or CMD+scroll wheel or something like that. Mousing over to select the color from the palette, then back over to where I want to draw, is slower.
Better color picker. I find the color picker in Pickle to be a step backward from the color picker in Paint.NET. I like when I can control the exact value of RGB or HSV or alpha and see the result as I change it. I find this helps me to select a color that I like fastest. The advanced color picker in Paint.NET is damn good: I really like being able to switch between using the color wheel, RGB/HSV sliders, and the value boxes to find and select the color I want very quickly.
Another great feature to include in a future iteration of the color picker would be a mode that makes it easy to pick colors schemes based on the theory of coloring presented in this tutorial — for each color added to the palette, the color picker could auto-suggest adjacent and complimentary color wheel suggestions, to enable better shading and highlighting, allowing the user to add them to the palette automatically if desired. This would be an AMAZING feature. The awesome web app Color Scheme Designer does it right.
Canvas and imaging Scaling/resizing! Scaling is a must-have feature which is currently missing. My favorite technique with pixel art is to rough in at very low resolution, then resize the image, doubling the resolution of the image, scaling it using Nearest Neighbor scaling so that no anti-aliasing artifacts are introduced, and then refining the details.
I can work extremely quickly when I work this way — i’ll start out at 16×16, and double a few times until I’m at 64×64, or 128×128, and those single pixels in the 16×16 rough version end up doing the work of a 8×8 block of pixels when I’ve scaled the rough image to 128×128, thereby saving me a factor of 64 pixels worth of work for each pixel that I rough in with the right color by the time I get to 128×128 resolution.
Being able to Select All, then CTRL+plus to double the canvas size, and CTRL+SHIFT+plus to double the canvas size while scaling up the image using Nearest Neighbor would be great. And to marquee-select, then CTRL+SHIFT+plus to scale the marquee selection 2x with Nearest Neighbor. (Essentially it’s like working with a large 8×8 brush tool, then switching to a 4×4, 2×2, and 1×1 brush, but it’s quick and easy for me to work this way.)
Arbitrary rotation: Currently Pickle only can rotate 90 degrees and mirror the image. Arbitrary rotation of the entire image, and pixel selections, would be extremely helpful. Not strictly necessary, as when you are manipulating pixels one at a time, you often want more precise control. But it can come in handy.