Cell-based compression of digital images

An article of manufacture including a non-transitory computer-readable medium, having stored thereon program instructions that, upon execution by a computing device, cause the computing device to perform operations comprising:

• obtaining an m×n pixel cell from an input image, wherein the input image contains more than m×n pixels, and each of the m×n pixels in the m×n pixel cell has a respective color value;
• determining a characterization of the m×n pixel cell, wherein determining the characterization comprises determining a lowest color value and a highest color value of the pixels in the m×n pixel cell;
• calculating a difference between the highest color value and the lowest color value;
• if the difference is less than or equal to a threshold difference, selecting an output color value inclusively between the highest color value and the lowest color value, and writing a first representation of the output color value to an output medium, wherein the first representation includes a single-color opcode and an indication of the output color value;
• and
• if the difference is greater than the threshold difference, selecting multiple output color values, and writing a second representation of the multiple output color values to the output medium.

A method comprising:

• a computing device obtaining an m×n pixel cell from an input image, wherein the input image contains more than m×n pixels, and each of the m×n pixels in the m×n pixel cell has a respective color value;
• the computing device determining a characterization of the m×n pixel cell, wherein determining the characterization comprises determining color values of the pixels in the m×n pixel cell;
• the computing device calculating a difference between a highest color value and a lowest color value of the color values;
• if the difference is less than or equal to a threshold difference, the computing device selecting an output color value inclusively between the highest color value and the lowest color value, and writing a first representation of the output color value to an output medium, wherein the first representation includes a single-color opcode and an indication of the output color value;
• else if the color values of the m×n pixel cell substantially consist of two color values, the computing device writing a second representation of the two color values to the output medium, wherein the second representation includes a two-color opcode, an indication of each of the two color values, and a per-pixel bitmap of the m×n pixel cell that associates each pixel in the m×n pixel cell with one of the two color values;
• else if the color values of the m×n pixel cell substantially consist of three or four color values, the computing device writing a third representation of the three or four color values to the output medium, wherein the third representation includes a four-color opcode, an indication of each of the three or four color values, and a per-pixel bitmap of the m×n pixel cell that associates each pixel in the m×n pixel cell with one of the three or four color values;
• and
• else if the color values of the m×n pixel cell substantially consist of more than four color values, the computing device performing a discrete cosine transformation (DCT) operation on the m×n pixel cell, and writing a fourth representation to the output medium, wherein the fourth representation includes a DCT opcode and a result of the DCT operation.