Arduboy image converters can be found in this thread:
The Sprites
class can be used to render sprites from a sprite sheet.
e.g.
Sprites::drawOverwrite(x, y, spriteSheet, spriteIndex);
The format for sprite sheets is the width of each sprite, followed by the height of each sprite, followed by the sprite data, each sprite one after another (they all have to be the same size).
The drawing code figures out where to look for each sprite by using the width and height and then doing some calculations to get the right byte offset.
Here’s an example of what a sprite sheet might look like:
constexpr uint8_t smallRabbitImageWidth = 8;
constexpr uint8_t smallRabbitImageHeight = 8;
const uint8_t smallRabbitImages[] PROGMEM =
{
// Dimensions
smallRabbitImageWidth, smallRabbitImageHeight,
// Frame 0 (North)
0x00, 0x78, 0x7E, 0x78, 0x78, 0x7E, 0x78, 0x00,
// Frame 1 (East)
0x00, 0x00, 0x78, 0x7E, 0x48, 0x78, 0x00, 0x00,
// Frame 2 (South)
0x00, 0x78, 0x4E, 0x78, 0x78, 0x4E, 0x78, 0x00,
// Frame 3 (West)
0x00, 0x00, 0x78, 0x48, 0x7E, 0x78, 0x00, 0x00,
};
(Sample taken from EasterPanic.)