The numbers following <code>geometry</code> indicate the resolution (1024x600) and the bits required to represent a pixel (32). The last line tells the pixel format (RGBA). In this case, 8 bits are used for each channel (reg, green, blue, and alpha) resulting in 32 bits combined. That is why the <code>depth</code> parameter of <code>convert</code> was set to 8and the format was set to <code>rgba</code>.