cristy@eplrx7.uucp (John Cristy) (07/24/90)
I am trying to determine the most optimal parameters and image format to XCreateImage that minimizes the work the server must do to display an image via XPutImage. I suspect creating the image data in the bit-order and byte-order of the server is most efficient, but I developed doubts when I looked at XImUtils.c and noticed the code normalizes all data to LSB byte-order and bit-order. Is it more efficient to generate the image data in LSBFirst byte-order and bit-order? Also are other parameters crucial in minimizing server overhead. For example, are 32 bit scanline pads more efficient than 8 bit? This is the last issue I need to resolve before I make my image processing software available on expo.lcs.mit.edu in a few days. A prompt reply will be appreciated. Please Email your suggestions to cristy@dupont.com. Thanks in advance. -- The UUCP Mailer
rws@EXPO.LCS.MIT.EDU (Bob Scheifler) (07/24/90)
I suspect creating the image data in the bit-order
and byte-order of the server is most efficient,
You are correct.
but I developed doubts when
I looked at XImUtils.c and noticed the code normalizes all data to
LSB byte-order and bit-order.
Um, the functions in that file are not used for XPutImage (at least, not
in the normal case). You asked specifically about XPutImage.
Also are other parameters
crucial in minimizing server overhead. For example, are 32 bit scanline
pads more efficient than 8 bit?
The scanline pad and bits per pixel should also be chosen to match what
the server wants.jimf@SABER.COM (07/25/90)
| Also are other parameters | crucial in minimizing server overhead. For example, are 32 bit scanline | pads more efficient than 8 bit? | |The scanline pad and bits per pixel should also be chosen to match what |the server wants. Yep, but I've found that it's not too bad to put the image in any format your program will be comfortable with and just feed that to the server. Even on gross architectures like the i386 machines this works reasonably well and it makes your imaging program a LOT simpler since it only has to deal with one image format. For a case study, you might look at my xloadimage program (I think I'm starting to sound like a preacher :-). It always builds ZPixmap format images (except for monochrome images) in MSByte order and feeds them to the server that way. Works pretty well. Xloadimage is available by anonymous ftp from expo.lcs.mit.edu in /contrib/xloadimage.1.06.tar.Z. Happy hacking, jim frost saber software jimf@saber.com