Instead of cluttering up cbm-hackers and making people mad, would you like me to set up a seperate mailing-list for Jeri's project? --- Jeri Ellsworth <cm_easy@yahoo.com> wrote: > I'll respond to your letters after the show... I'm > very interested in > what you are doing. > > Jeri > --- "Hársfalvi, Levente" <levente@terrasoft.hu> > wrote: > > Hi! > > > > > > I'm having some problems with the gfxconv stuff > I'm working on (...as > > usual > > :-/ ). ...At first, sorry for the long letter; > just delete if you're > > not > > interested in color optimization issues. > > > > This routine is intended to take raw 24 bit > 320x400 images and > > convert them > > to the C64 styled, enhanced multicolor mode of > Jeri's new videoboard > > (in the > > same resolution). I'm at the last stage of the > optimizer algorithm. > > Things > > like reducing the number of colors, picking up a > suitable value for > > background color and selecting color triads for > each 4x8 color blocks > > are > > done (and work O.K. as far as I'm concerned). > > > > (Just for a short explanation: the mode works > exactly as the usual > > multicolor bitmap mode, except for the resolution > and the colors. The > > resolution is just 'expanded', no real change in > the organization. > > For the > > color thing: there is a color palette with 256 > entries (instead of > > the > > original fixed 16 color long 'palette'). Color > registers (like > > background > > and the others) are treated like 8 bit indexes to > this palette (all 8 > > bits > > are used, instead of 4 bits like the original VIC > did). In bitmap > > modes, the > > situation is similar, with one addition: the color > memory values (the > > usual > > 4 bit nibbles) give the low 4 bit nibbles of the > index. The higher 4 > > bit > > nibble is given by the high 4 bits of the color > RAM, and this higher > > 4 bit > > is common for all color indexes in the respective > 4x8 color block.). > > > > There is a problem. In MC mode, the above (last) > rule means that all > > 3 MC > > colors for color blocks must be in one (16 colors > long) palette > > chunk. > > (Different color blocks can select colors from > different chunks, of > > course). > > No problem when it's just one, or a few blocks -- > but this rule must > > be > > taken into account for _all_ such color blocks in > the image, creating > > a > > heavy dependence between colors. > > > > (Quick calculation shows that if there are just 20 > colors on the > > whole > > image, and each colors are featured with the other > colors in the > > image at > > least once, with the above organization they > occupy exactly 256 > > places from > > the palette.) > > > > I inserted a small code piece that listed out the > color dependencies > > on the > > test image and the results are hmmm... > 'embittering'. When using > > color > > reduction to just 64 colors for the whole image, > some colors depended > > on > > 30-40 other colors in the map. > > > > I think I know the 'direction', just don't know > the way. I hope > > someone did > > similar programming tricks, so he could give me > some help. > > > > Imagine an X*X type symmetrical matrix, where X is > the total number > > of > > colors in the image. If there's a '+' in the (i,j) > position of the > > matrix, > > that means that the two colors (i, and j) were > found in the same > > color block > > of the image at least once (ie. they're > dependent). (Crosses in the > > (i,i) > > positions correspond to the fact that the i-th > color was found in the > > image > > at least once (ie. 'dependent on just itself')). > The problem to be > > solved: > > form <=16 disjunct groups from the above > dependency matrix, where > > each > > disjunct groups include <= 16 elements, with the > possible least > > number of > > ignored dependencies. > > > > ...Well, this is what is above me at the moment. > Anyone with some > > ideas on a > > working algorithm?... > > > > > > Thanks, > > > > L. > > > > - > > This message was sent through the cbm-hackers > mailing list. > > To unsubscribe: echo unsubscribe | mail > cbm-hackers-request@dot.tml.hut.fi. > > > __________________________________________________ > Do You Yahoo!? > Yahoo! Auctions - buy the things you want at great > prices > http://auctions.yahoo.com/ > - > This message was sent through the cbm-hackers > mailing list. > To unsubscribe: echo unsubscribe | mail cbm-hackers-request@dot.tml.hut.fi. ===== Get a FREE 6Mb webmail box from go6502! - http://www.geocities.com/profdredd PayPal - The FAST FREE and SECURE way to send money. https://secure.paypal.x.com/refer/pal=profdredd%40yahoo.com __________________________________________________ Do You Yahoo!? Yahoo! Auctions - buy the things you want at great prices http://auctions.yahoo.com/ - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail cbm-hackers-request@dot.tml.hut.fi.
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