cs__sjh@umt.UUCP (Jeffrey Heng) (03/01/90)
Hi, I'm currently trying to do some mac programming using Color QuickDraw. Can anyone recommend a good book on Color QuickDraw (other than Inside Macintosh Vol. V) ? I'm trying to change the color lookup tables to explore the various effects on my scanned in pictures. Right now I'm able to display the scanned in pictures using SetPixel. I've encountered the following problem when exploring with different lookup tables: In the first case, I set up a color lookup table with 256 shades of gray and then used this CLUT to display a picture using SetPixel. In the second case, I used the default lookup table to draw the same picture. After this picture was displayed, I changed the CLUT to 256 shades of gray without redrawing and I get a picture of poorer quality than in the first case. Why is this so? What is the colorSpec.value field for ? It appears to be different for gDevice and pixmap. I also realise that the 32-Bit quickdraw does change the grayscale pictures that I draw. Can anyone out there answer some of these questions ? I'd appreciate any help. Thank you. Jeff
oster@well.sf.ca.us (David Phillip Oster) (03/11/90)
>I'm trying to change the color lookup >tables to explore the various effects on my scanned in pictures. If you are using an 8-bit deep display, remember to change the palette of the top window when you change its color table. This will make sure you really get the colors you ask for. Also, remember that when you do a CopyBits(), is the src and dest have different color tables, the inverse table of the current graphic device is used to figure out the mapping of colors from src to dest. If the color table of the gDevice is too different from the dest pixmap, you won't get high quality pictures. -- -- David Phillip Oster - Note new address. Old one has gone Bye Bye. -- oster@well.sf.ca.us = {backbone}!well!oster Newsgroups: poster Subject: Re: Color QuickDraw and 32Bit Quickdraw Summary: Expires: References: <833@umt.UUCP> Sender: Reply-To: oster@well.UUCP (David Phillip Oster) Followup-To: Distribution: Organization: Whole Earth 'Lectronic Link, Sausalito, CA Keywords: Color QuickDraw In article <833@umt.UUCP> cs__sjh@umt.UUCP (Jeffrey Heng) writes: >I'm trying to change the color lookup >tables to explore the various effects on my scanned in pictures. If you are using an 8-bit deep display, remember to change the palette of the top window when you change its color table. This will make sure you really get the colors you ask for. Also, remember that when you do a CopyBits(), is the src and dest have different color tables, the inverse table of the current graphic device is used to figure out the mapping of colors from src to dest. If the color table of the gDevice is too different from the dest pixmap, you won't get high quality pictures. -- -- David Phillip Oster - Note new address. Old one has gone Bye Bye. -- oster@well.sf.ca.us = {backbone}!well!oster