| 63 | | In this case, `img2twit`'s approach would be to use 40 values of each component, where the RGB triplet is computed as ''(((R) * 40 + G) * 40 + B)'', and eg. the green value is retrieved as ''(RGB / 40) % 40''. This makes the computations a lot slower (modulo 64 is just a bit shift, while modulo 40 requires dividing the whole bitstream by 40). However, it offers better packing and a lot more control over the data representation. For instance, I found that 2 bits (4 values) per colour component was not enough, but that 3 bits (8 values) was more than required. I went for 6 values (2.58 bits). |
| | 63 | In this case, `img2twit`'s approach would be to use 40 values for each component, where the RGB triplet is computed as ''(((R) * 40 + G) * 40 + B)'', and eg. the green value is retrieved as ''(RGB / 40) % 40''. This makes the computations a lot slower (modulo 64 is just a bit shift, while modulo 40 requires dividing the whole bitstream by 40). However, it offers better packing and a lot more control over the data representation. For instance, I found that 2 bits (4 values) per colour component was not enough, but that 3 bits (8 values) was more than required. I went for 6 values (2.58 bits). (Sidenote: in fact, in order to cram even more information into the 16 bits, it would use 39/48/35 in this particular case.) |
