Re: 8 bit pixel in memory blits

> StretchDIBits can do this without palettes if you specify DIB_RGB_COLORS and fill in the bmiColors array in the BITMAPINFO structure. The destination DC should contain a bitmap created with CreateDIBSection, again specifying DIB_RGB_COLORS and a valid bmiColors array.

What is bmiColors for, if not a palette?
That was probably my problem, but I did find out the amazing fact that the processor is so fast, that converting the 8-bit to 32 bit, doing the operation, and converting back to 8-bit, took a millisecond or less.  Amazing! I guess my bitmaps are not so big also. (maybe up to 500 on a side)
Thanks
Todd.





--- In [email protected], "Jim Barry" <j.barry@...> wrote:
>
> "todd" <timza1221@...> wrote:
> > Does anyone know if 8 bit per pixel StretchDIBits() blits can be done 
> > in-memory?
> > Is a palette required for the bitmaps and if so is SelectPalette() 
> > required?
> > Having trouble maintaining the 8-bit (gray scale) colors.
> 
> What exactly are you trying to do? Stretch an 8bpp DIB into another? 
> StretchDIBits can do this without palettes if you specify DIB_RGB_COLORS and 
> fill in the bmiColors array in the BITMAPINFO structure. The destination DC 
> should contain a bitmap created with CreateDIBSection, again specifying 
> DIB_RGB_COLORS and a valid bmiColors array.
> 
> You should call SetStretchBltMode(STRETCH_DELETESCANS) for the destination 
> DC - the default is STRETCH_ANDSCANS which causes strange results when 
> shrinking. Note that StretchDIBits is only capable of a very low-quality 
> "pixel resize". For anything better, e.g. interpolation or pixel averaging, 
> you'd need to use something other than StretchDIBits.
> 
> - Jim
>




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