Re: Re: ImageMagick too slow

I take it the image manipulation is different every time, so you can't cache the resulting scaled/manipulated image?
Yes, the number of possible combinations is so high that creating cached copies of each possible image would require too much space and processing time.

What kind of transformations are you doing? It's probably possible to "stream" the JPEG decoding and processing through a pipeline in one pass, as opposed to reading the whole thing and consuming 12 meg of ram, then performing different passes for each part of the process, then encoding the result.
ImageMagick currently processes the following transformations: crop, scale, extract channel, composite image, clone, and add decorative frames. I like the idea of computing these transformations as the JPEG is processed. Logically, I think that the transformations don't need a full image to be computed. However, because sometimes five or more of these transformations are computed in a row, and sometimes ImageMagick splits one image into two separate images and then computes transformations, they will need to be loaded into RAM at some point. I sense that your idea of streaming would speed things up quite a bit. I will look futher into this idea - does anyone have any input on this one?

Thanks for your ideas.

Comment on Re: Re: ImageMagick too slow

Replies are listed 'Best First'.
Re^3: ImageMagick too slow by zengargoyle (Deacon) on Dec 27, 2002 at 09:56 UTC
netpbm might do what you wish. there are hundreds of programs, most suitable for streaming together. $ djpeg foo.jpg \| pnmscale -xy 100 100 \| cjpeg -smoo 10 -qual 50 >smal +l.jpg SEE ALSO anytopnm(1), asciitopgm(1), atktopbm(1), bioradtopgm(1), bmptoppm(1), brushtopbm(1), cmuwmtopbm(1), fitstopnm(1), fstopgm(1), g3topbm(1), gemtopbm(1), giftopnm(1), gould- toppm(1), hipstopgm(1), hpcdtoppm(1), icontopbm(1), ilbmtoppm(1), imgtoppm(1), lispmtopgm(1), macptopbm(1), mgrtopbm(1), mtvtoppm(1), pbmclean(1), pbmlife(1), pbmmake(1), pbmmask(1), pbmpscale(1), pbmreduce(1), pbmtext(1), pbmto10x(1), pbmto4425(1), pbmtoascii(1), pbmtoatk(1), pbmtobbnbg(1), pbmtocmuwm(1), pbmtoepsi(1), pbmtoepson(1), pbmtog3(1), pbmtogem(1), pbmtogo(1), pbmtoi- con(1), pbmtolj(1), pbmtoln03(1), pbmtolps(1), pbmtomacp(1), pbmtomgr(1), pbmtopgm(1), pbmtopi3(1), pbmtopk(1), pbmto- plot(1), pbmtoptx(1), pbmtox10bm(1), pbmtoxbm(1), pbmtoybm(1), pbmtozinc(1), pbmupc(1), pcxtoppm(1), pgmbent- ley(1), pgmcrater(1), pgmedge(1), pgmenhance(1), pgmhist(1), pgmkernel(1), pgmnoise(1), pgmnorm(1), pgmoil(1), pgmramp(1), pgmtexture(1), pgmtofs(1), pgmtolispm(1), pgmtopbm(1), pgmtoppm(1), pi1toppm(1), pi3topbm(1), picttoppm(1), pjtoppm(1), pktopbm(1), pnmalias(1), pnmar- ith(1), pnmcat(1), pnmcomp(1), pnmconvol(1), pnmcrop(1), pnmcut(1), pnmdepth(1), pnmenlarge(1), pnmfile(1), pnmflip(1), pnmgamma(1), pnmhistmap(1), pnmindex(1), pnmin- vert(1), pnmmargin(1), pnmnlfilt(1), pnmnoraw(1), pnmpad(1), pnmpaste(1), pnmrotate(1), pnmscale(1), pnmshear(1), pnmsmooth(1), pnmtile(1), pnmtoddif(1), pnmtofits(1), pnmtops(1), pnmtorast(1), pnmtosgi(1), pnmtosir(1), pnmto- tiff(1), pnmtoxwd(1), ppm3d(1), ppmbrighten(1), ppmchange(1), ppmdim(1), ppmdist(1), ppmdither(1), ppmflash(1), ppmforge(1), ppmhist(1), ppmmake(1), ppmmix(1), ppmnorm(1), ppmntsc(1), ppmpat(1), ppmquant(1), ppmquan- tall(1), ppmqvga(1), ppmrelief(1), ppmshift(1), ppmspread(1), ppmtoacad(1), ppmtobmp(1), ppmtogif(1), ppmtoicr(1), ppmtoilbm(1), ppmtomap(1), ppmtomitsu(1), ppmtopcx(1), ppmtopgm(1), ppmtopi1(1), ppmtopict(1), ppmtopj(1), ppmtopjxl(1), ppmtopuzz(1), ppmtorgb3(1), ppmto- sixel(1), ppmtotga(1), ppmtouil(1), ppmtoxpm(1), ppmtoyuv(1), ppmtoyuvsplit(1), psidtopgm(1), pstopnm(1), qrttoppm(1), rasttopnm(1), rawtopgm(1), rawtoppm(1), rgb3toppm(1), sgitopnm(1), sirtopnm(1), sldtoppm(1), spctoppm(1), spottopgm(1), sputoppm(1), tgatoppm(1), tifftopnm(1), xbmtopbm(1), ximtoppm(1), xpmtoppm(1), xvmini- toppm(1), xwdtopnm(1), ybmtopbm(1), yuvsplittoppm(1), yuvtoppm(1), zeisstopnm(1) [download]	[reply] [d/l]
Re: Re^3: ImageMagick too slow by lpoht (Sexton) on Dec 28, 2002 at 21:54 UTC
Thanks for your help, zengargoyle - these tools look very promising. However, the windows port of cjpeg seems to expect a named file as an input, rather than accepting data from the standard input. I'm not much of a serious programmer, and would not be able to edit the source code or anything, but was wondering if you might be able to shed some light on this problem. Thanks	[reply]
Re: Re: Re: ImageMagick too slow by John M. Dlugosz (Monsignor) on Dec 27, 2002 at 15:40 UTC
Perhaps finding or making a tool that will crop and scale in one pass while "loading" will give you most of the benifit. Then you have data for a screen-sized image, which is much smaller than the original. I beleive you need to keep three rows on hand in order to do bicubic interpolation to resample the image. For cropping, you can throw away whole blocks and not even process them; though you still have to read through it because you don't know the length ahead of time. Look at the code ImageMagick uses to read a JPEG file. I beleive that is the independent free JPEG source.	[reply]