In an embodiment, a method involves receiving a pixel array, compressing the pixel array by, for each pixel block of multiple pixel blocks: accessing pixel values associated with pixels in the pixel block, determining a range of the pixel values and an endpoint pixel value in the range, determining quantization levels corresponding to different values within the range of the pixel values, selecting a quantization level from the quantization levels for each of the pixel values in the pixel block, and encoding the pixel values in the pixel block using their respective selected quantization levels and the endpoint pixel value.