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Julian Hall wrote:
>
> Does GIMP have this functionality?
GIMP has a batch mode, and can also have modules added (including Python).
> Tedious to do it for every picture, but better than doing every step
> manually.
The netpbm tools are far better for bulk image manipulation.
Of course you need some basic shell scripting skills, but it is so
useful (and cool) to be able to resize, crop, and handle so many
different image formats, so quickly.
http://netpbm.sourceforge.net/doc/#prognotes
The example above show, converting png to jpeg (why?), and how to
brighten and image, but there are a lot of other programs in the suite.
Say you have some "png" files and you want them all the same width as
they'll all appear on the same web page template, and saved as "jpeg"
files because the customer likes jpeg for some weird reason, but you
don't want any compression artifacts introduced into the jpegs.
So you start with a set of files....
for afile in photodir/*.png
do
....magic goes here...
done
The first step in the pipeline is usually to covert the image to pnm, so
there are a load of programs names {imageformat}topnm.
"pngtopnm $afile |"
Then we want to make the resulting "pnm" the same width (say 200).
"pnmscale -xsize=200 |"
Then we want to convert to a jpeg, but preserve the quality.
"pnmtojpeg -quality=100"
And then save it to a file ">$afile.jpeg".
Putting it together;
for afile in photodir/*.png
do
pngtopnm $afile | pnmscale -xsize=200 | pnmtojpeg -quality=100 >$afile.jpeg
done
And you can use "mmv" to rename them if the ".png.jpeg" ending offends
your sensibilities.
It may seem a bit weird at first, but this is exactly how Unix/Linux was
suppose to be used. Lots of small programs, that are efficient and do
one task well, that hook together to produce a flexible system. If one
step in the pipeline fails, it just skips that image.
I use netpbm for thumbnails for product images for customer sites, and
that sort of thing. But because the programs mostly have obvious names
you can usually just type "pnm" (or type a graphic extension like
"png"), and use the Bash shell tab auto-completion to find which program
you need. Each program has a standard manual page, that explains its
options.
Here is a list of the programs in Debians netpbm package.....
411toppm anytopnm asciitopgm atktopbm bioradtopgm bmptopnm bmptoppm
brushtopbm cmuwmtopbm eyuvtoppm fiascotopnm fitstopnm fstopgm g3topbm
gemtopbm gemtopnm giftopnm gouldtoppm hipstopgm icontopbm ilbmtoppm
imgtoppm jpegtopnm leaftoppm lispmtopgm macptopbm mdatopbm mgrtopbm
mtvtoppm neotoppm palmtopnm pamcut pamdeinterlace pamdice pamfile pamoil
pamstack pamstretch pamstretch-gen pbmclean pbmlife pbmmake pbmmask
pbmpage pbmpscale pbmreduce pbmtext pbmtextps pbmto10x pbmtoascii
pbmtoatk pbmtobbnbg pbmtocmuwm pbmtoepsi pbmtoepson pbmtog3 pbmtogem
pbmtogo pbmtoicon pbmtolj pbmtomacp pbmtomda pbmtomgr pbmtonokia
pbmtopgm pbmtopi3 pbmtoplot pbmtoppa pbmtopsg3 pbmtoptx pbmtowbmp
pbmtox10bm pbmtoxbm pbmtoybm pbmtozinc pbmupc pcxtoppm pgmbentley
pgmcrater pgmedge pgmenhance pgmhist pgmkernel pgmnoise pgmnorm pgmoil
pgmramp pgmslice pgmtexture pgmtofs pgmtolispm pgmtopbm pgmtoppm
pi1toppm pi3topbm pjtoppm pngtopnm pnmalias pnmarith pnmcat pnmcolormap
pnmcomp pnmconvol pnmcrop pnmcut pnmdepth pnmenlarge pnmfile pnmflip
pnmgamma pnmhisteq pnmhistmap pnmindex pnminterp pnminterp-gen pnminvert
pnmmargin pnmmontage pnmnlfilt pnmnoraw pnmnorm pnmpad pnmpaste pnmpsnr
pnmquant pnmremap pnmrotate pnmscale pnmscalefixed pnmshear pnmsmooth
pnmsplit pnmtile pnmtoddif pnmtofiasco pnmtofits pnmtojpeg pnmtopalm
pnmtoplainpnm pnmtopng pnmtops pnmtorast pnmtorle pnmtosgi pnmtosir
pnmtotiff pnmtotiffcmyk pnmtoxwd ppm3d ppmbrighten ppmchange ppmcie
ppmcolormask ppmcolors ppmdim ppmdist ppmdither ppmfade ppmflash
ppmforge ppmhist ppmlabel ppmmake ppmmix ppmnorm ppmntsc ppmpat ppmquant
ppmquantall ppmqvga ppmrainbow ppmrelief ppmshadow ppmshift ppmspread
ppmtoacad ppmtobmp ppmtoeyuv ppmtogif ppmtoicr ppmtoilbm ppmtojpeg
ppmtoleaf ppmtolj ppmtomap ppmtomitsu ppmtompeg ppmtoneo ppmtopcx
ppmtopgm ppmtopi1 ppmtopict ppmtopj ppmtopuzz ppmtorgb3 ppmtosixel
ppmtotga ppmtouil ppmtowinicon ppmtoxpm ppmtoyuv ppmtoyuvsplit ppmtv
psidtopgm pstopnm qrttoppm rasttopnm rawtopgm rawtoppm rgb3toppm
rletopnm sbigtopgm sgitopnm sirtopnm sldtoppm spctoppm sputoppm st4topgm
tgatoppm thinkjettopbm tifftopnm wbmptopbm winicontoppm xbmtopbm
ximtoppm xpmtoppm xvminitoppm xwdtopnm ybmtopbm yuvsplittoppm yuvtoppm
zeisstopnm
I'm told you can usually ignore (pbm, pgm, ppm) as they are hidden
behind the "pnm" commands most of the time. Certainly I get everything I
need done with "pnm" commands.
The pnm ones....... you can just guess what half of them do.
anytopnm bmptopnm fiascotopnm fitstopnm gemtopnm giftopnm jpegtopnm
palmtopnm pngtopnm pnmalias pnmarith pnmcat pnmcolormap pnmcomp
pnmconvol pnmcrop pnmcut pnmdepth pnmenlarge pnmfile pnmflip pnmgamma
pnmhisteq pnmhistmap pnmindex pnminterp pnminterp-gen pnminvert
pnmmargin pnmmontage pnmnlfilt pnmnoraw pnmnorm pnmpad pnmpaste pnmpsnr
pnmquant pnmremap pnmrotate pnmscale pnmscalefixed pnmshear pnmsmooth
pnmsplit pnmtile pnmtoddif pnmtofiasco pnmtofits pnmtojpeg pnmtopalm
pnmtoplainpnm pnmtopng pnmtops pnmtorast pnmtorle pnmtosgi pnmtosir
pnmtotiff pnmtotiffcmyk pnmtoxwd pstopnm rasttopnm rletopnm sgitopnm
sirtopnm tifftopnm xwdtopnm zeisstopnm
Now why would I want to do this in something like the GIMP, often I'm
done before the GIMP would finish loading? Although a "previewing file
managers" which show a thumbnail view of every image in a directory is a
great help here, as you can spot when you mess up quickly.
Anyone fancy a play -- try writing a script that makes outline/sketch
like versions of a directory of images, all at the same small size,
using png, and then looks around for a tool that ensures all the png
files are as small as possible. pnmconvol can be used as a kind of
Gaussian filter to do this. The ambitious can then add borders to them,
and mount them in montages. It should be much more than the example given.
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