Table of Contents
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Graphics on the command line
Description of Exif file format
Commands
Official Debian image viewer packages with high relevance
| Command | Explanation | Remark |
|---|---|---|
| cjpeg / djpeg | Convert to/from the JPEG file format | Part of libjpeg-turbo-progs |
| convert | Convert between image formats as well as resize an image, blur, crop, despeckle, dither, draw on, flip, join, re-sample, and much more | Part of imagemagick |
| display | Displays an image or image sequence on any X server | Part of imagemagick |
| exif | ||
| exiftags | ||
| exiftran | Digital camera JPEG image transformer | |
| exiv2 | ||
| jhead | jpeg exif editor | |
| jpegpixi | Remove hot spots from JPEG images with minimal quality loss | |
| feh | Image viewer and cataloguer | |
| imagemagic | Create, edit, compose, or convert bitmap images in over 200 formats | |
| imagetops | Generic image to ps filter | |
| jpegexiforient / exifautotran | Manipulate EXIF orientation tag | Part of libjpeg-turbo-progs |
| jpegtopnm | Convert JPEG/JFIF file to portable pixmap or graymap | |
| jpegtran | Lossless transformations of JPEG files | Part of libjpeg-turbo-progs |
| libjpeg-turbo-progs | programs for manipulating JPEG files | |
| rdjpgcom / wrjpgcom | Read/write comments in JPEG files | Part of libjpeg-turbo-progs |
| renrot | Rename and rotate files according to EXIF tags | |
| scrot | Screen capture utility | |
| tjbench | A simple JPEG benchmarking tool | Part of libjpeg-turbo-progs |
| trend | General-purpose, efficient trend graph | |
| webp | Convert a webp picture to png | dwebp picture.webp -o picture.png. Other commands: cwebp (encoder)tool, dwebp (decoder), vwebp (viewer), wepmux (muxing tool), gif2webp (convert GIF images to WebP) |
| Xli | Command line tool for viewing images in X11 |
Screenshot
| -delay | In milliseconds |
| -window root | Full screen |
import -window root -resize 1920x1080 -delay 2000 screenshot.png
feh Show pictures
Save modified files
If you want files to be saved when the --edit option is applied aptitude install libjpeg-turbo-progs which contains the commandline tools mentioned above
So do feh --edit file.jpg Any modification is saved when feh is closed
Modifing keybindings
| Key | Action | Remark |
|---|---|---|
| Backspace | Show previous file | |
| Ctrl+Delete | Delete the file | |
| < > | Rotation | From Debian 10 Buster use --edit if you want the modified file to be saved |
| | _ | Mirroring | From Debian 10 Buster onwards use --edit if you want the modified file to be saved |
Command examples
Show all pictures in a folder
feh --fullscreen --hide-pointer --draw-exif --draw-filename * feh --geometry 800x450 --hide-pointer --draw-filename --edit --scale-down *
Show all pictures in a folder and all subfolders and scale to the sreen size
feh --recursive --scale-down *
Show all pictures in the folder in a 400×400 pixels window with a delay of 0.2 seconds once
feh --geometry 400x400 --slideshow-delay=0.2 --cycle-once
Errors
feh ERROR: Can't open X display. It *is* running, yeah?
Colors
xcolors - display all X11 color names and colors
convert (scale, resize)
| Command | Description |
|---|---|
| identify -format “%wx%h\n” * | Show the size of all picutres in the current directory |
| convert test.png test.jpg | |
| convert test.jpg -resize 600×400\> test.jpg | Converts the image to a 600 x 400 image |
| convert test.png -resize 400 test400.png | Converts the image to a 400 width image while maintining the aspect ratio |
convert '*.jpg[800x>]' item-%02d.jpg | Converts all .jpg files in the directory to files with a width of 800 while maintiaining the aspact ratio and changing the filename to something like item-03.jpg where the number counts from 00. If the width is 800 or less the image is not scaled |
for i in `ls test*.png`; do basename1=`echo $i | \ cut -d \. -f 1`; convert $i -resize 400 \ $basename1.400.png; done | Convert multiple images named test*.png to a 400 pixel width and name them test*.400.png |
for i in *.BMP; do convert $i "${i%.BMP}.png"; done | Convert all .BMP files in the directory to .png files |
convert -resize x16 -gravity center -crop 16x16+0+0 \ -flatten -colors 256 -background transparent \ image.png favicon.ico | Convert image.png to a favicon of size 16 x 16 pixels |
convert "filename.ext" -rotate 90 "filename-r.ext" ; |
Contrast, brightness
convert -brightness-contrast 20x30 test.jpg testbricon.jpg
| Increase the brightness with 20 and the contrast with 30 |
Convert
netpbm - package of graphics manipulation programs and libraries
Convert a pdf file made in RGB to CMYK with gs. This should work, it did not for us
gs -dSAFER -dBATCH -dNOPAUSE -dNOCACHE -sDEVICE=pdfwrite \ -sColorConversionStrategy=CMYK -dProcessColorModel=/DeviceCMYK \ -sOutputFile=output.pdf input.pdf
Convert a tiff file made in RGB to CMYK with Imagemagick's convert tool
Compression might be needed
convert source.tiff -colorspace CMYK -compress LZW destination.tiff
Optional commands
convert -list colorspace convert -list compress
Merge
Merge two or more pdf files (example with 3 input files)
pdfunite file1.pdf file2.pdf fil3.pdf outfile.pdf
Crop
- Install imagemagick
- Run display imagefile.extension
- You can zoom with the < and > keys
- Left click in the image to open the menu. Rightclick gives an other menu
- Select Transform | Crop
- Crop the image
- File | Save
- Select a file name and change it as needed
- Save
- Enger JPEG quality 75 Save
- File | Quit
display
Some keyboard accelerators for the display command:
| Key | Function |
|---|---|
| Space | Next image |
| Backspace | Previous image |
| / | Rotate by 90 degrees clockwise |
| \ | Rotate by 90 degrees counter clockwise |
| < | Zoom out |
| > | Zoom in |
| Esc | Quit |
More on display keyboard accelerators
Create animated gif
GIF: Graphics Interchange Format
convert -delay 10 -loop 0 *.png file.gif
The default delay tick is 1/100 of a second. So 10 → 1/10 th of a second
For two seconds use 200 or 2/1
Loop 0 means infinite number of loops
Save picture from clipboard
xclip -selection clipboard -t TARGETS -o
Now save all, since the image can be multi layer, the image/something instances where something can be png, bmp, jpg, and so on
xclip -selection clipboard -t image/png -o > /tmp/image.png xclip -selection clipboard -t image/bmp -o > /tmp/image.bmp
Webcam
fswebcam
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