On Mon, 13 Feb 2012, Charlie wrote:
On 2/13/2012 7:37 AM, Vladimir Ivanov wrote:On Sun, 12 Feb 2012, Charlie wrote:I have yet to see an algorithm that correctly produces a DHR picture. The exception being those who used very large look-up tables to cover every case of color changes. That's something I don't have the luxury of in the Carte Blanche card.How much memory you have available for lookup?The Carte Blanche card has 250Kbytes of SRAM but that isn't practical to use for a lookup table since we're using it to read/write some of the video buffer. The internal FPGA BRAM is only about 24KBytes and that's virtually all used.
Too bad. My experiments showed that 9-bit lookup vector is quite nice looking for NTSC emulation. This needs 4 tables of 512 entries, each entry being your DAC triplet output (12-bit or less, I assume).
Check sample 6, 9, 12 and 24-bit lookup vectors here: http://www.softjunk.org/sw/apple2/ra2/files/screenshot/ntsc/bpp/
The IIgs simple yet effective mode you can already implement in few hours. :-)If you are talking about the SHR mode it's already done. :-)
No, about the IIgs DHGR mode - the non-linear 4-bit sliding window from that US patent. It's very simple and effective.