Fewer Colors

Other recommendations might include lower-resolution color formats. A lot of imagery would look almost as good at only 16 bits vs. 32, especially if there is no alpha mask. Android's default format is the ever-popular RGB565, which means it has 5 bits red, 6 bits for green, and 5 bits for blue. (The green color is given a boost because our eyes are most sensitive to it.) Other 16-bit formats include RGBA5551 or RBGA4444. On Distant Suns, my grayscale constellation artwork is only 8 bits, cutting memory usage by 75 percent. Should I want it tinted to match a specific theme, I let OpenGL do the work. With the proper tool and careful tweaking, some 16-bit textures are almost indistinguishable from the 32-bitters.

Figure 9–4 illustrates four of these formats created by TexturePacker, with the highest to lowest quality going from left to right. Image 1 shows the true-color texture we've been using, sometimes called RGBA8888. Image 2 uses the default RGB565 format that still looks quite good, considering. Image 3 in Figure 9–4 uses RGBA5551, allocating a 1-bit alpha channel (notice how much a difference the extra bit for green makes when compared to the previous texture), and image 4 is the lowest quality, using RGBA4444. TexturePacker also supports the PVRTC file types referenced in Chapter 5.