On Sun, May 23, 2021 at 4:33 AM Thomas Schmitt <scdbac...@gmx.net> wrote:
> Hi, > > Dan Hitt wrote: > > Thomas, that sounds awesome, please do post somewhere (and provide a link > > here, if you would be so kind). > > So on popular demand by one potential user here it is > > http://scdbackup.sourceforge.net/halve_jpeg.c > > SHA256SUM: > b4c9322cd7d20a09a5196ccbcec257bf363d9dea1284333afc9624ff6a05dcc0 > > It needs installed libjpeg development header files and runtime library. > To my theory that would be package "libjpeg62-turbo-dev" which brings > the runtime as dependency. > The tools for compilation get installed by meta-package "build-essential". > > Compile the program by > > cc -g -Wall -o halve_jpeg halve_jpeg.c -ljpeg > > Test by converting some file > > ./halve_jpeg -geometry 1280x1024 large_input_pic.jpg > ermerging_small_pic.jpg > > xv ermerging_small_pic.jpg > > The -geometry argument defines a frame into which ermerging_small_pic.jpg > will fit while retaining its x:y ratio. > > For permanent use, copy the file ./halve_jpeg to a directory where the > shell > will find it. > > It is not very good with enlarging images. My motivation was to condense > JPEGS with zillions of pixels to screen size without blasting my RAM which > was only 2 GB at that time. > > > Have a nice day :) > > Thomas > > Thanks Thomas for posting it. On xubuntu 20.2 i was able to compile it after installing some jpeg packages: sudo apt-get install jpeginfo libjpeg-dev libjpeg-progs libjpeg-tools I think some of these names may be generic and point to the turbo code, i'm not sure. I tried just installing all jpeg packages but got conflicts, so i pared down the list until i could install. The code compiled quickly. It was unwilling to deal with a non-color image that i had ("Unsuitable JPEG format with 1 components per pixel"), but on color images it works and is very fast. And since you were so nice to provide the source code, if i need to deal with non-color images, i can try to modify it. Thanks again! dan
