[SOLVED] Help with bash script using identify from imagemagick

Pedroski · 02-05-2024, 01:40 PM

I want to get the number of different colours in each image from a folder with images.

identify will give me the sizes:

Quote:

pedro@pedro-HP:~/Downloads$ identify -format %k /home/pedro/Downloads/what_does_this_say.jpg
34089pedro@pedro-HP:~/Downloads$

The jpg what_does_this_say.jpg has 34089 different colours.

Now I want to save all the image names and sizes in an array, or better, a text file, each image and colour count on a new line.

I don't know how bash reads the files in, that is to say, I don't know which file would be first in a list and how the list is ordered, so an array name:colour count would be best.

I thought I could do this, but it doesn't work:

Quote:

path2files="/home/pedro/Downloads/"
for f in $path2files*.jpg;
do
echo "$f"
size = identify -format %k $f
echo "$size"
done

I get this error for each file: size: invalid option -- 'r'

Quote:

/home/pedro/Downloads/what_does_this_say.jpg
size: invalid option -- 'r'
Usage: size [option(s)] [file(s)]
Displays the sizes of sections inside binary files
If no input file(s) are specified, a.out is assumed
The options are:
-A|-B|-G --format={sysv|berkeley|gnu} Select output style (default is berkeley)
-o|-d|-x --radix={8|10|16} Display numbers in octal, decimal or hex
-t --totals Display the total sizes (Berkeley only)
--common Display total size for *COM* syms
--target=<bfdname> Set the binary file format
@<file> Read options from <file>
-h --help Display this information
-v --version Display the program's version

size: supported targets: elf64-x86-64 elf32-i386 elf32-iamcu elf32-x86-64 pei-i386 pe-x86-64 pei-x86-64 elf64-l1om elf64-k1om elf64-little elf64-big elf32-little elf32-big pe-bigobj-x86-64 pe-i386 srec symbolsrec verilog tekhex binary ihex plugin

Any tips please?

michaelk · 02-05-2024, 01:58 PM

Code:

size=$(identify -format %k "$f")

You can not have spaces between the = in a statement, use $() which is called command substitution and put quotes around the file name variable.

To check script syntax use https://www.shellcheck.net/

To save the file name:color you can use a redirect i.e.

echo "$f:$size" >> /path/to/file

The ">>" appends the line to the end of the file.

Pedroski · 02-06-2024, 02:30 AM

Thanks a lot!

I used this:

Quote:

#!/bin/bash
path2files="/home/pedro/Downloads/"
for f in $path2files*.jpg;
do
echo "$f"
# this works
colours=$(identify -format %k $f)
echo "$colours"
echo "$f:$colours" >> /home/pedro/Downloads/colours.txt
done

it worked great!

Is it possible to tell bash to rewrite the file from scratch if I do this again? Or create the file new each time?

The second time I tried, bash append to the existing file.

Later, I want to use Python PIL to get the colour count of each colour: read in the text file, split each line on : /home/pedro/Downloads/1695363058057.jpg:70419

Code:

data = line.split(':')
img = data.split[0]
num = data.split[1]
# now set maxcolors = num
im = Image.open(img).convert("RGB")
im1 = Image.Image.getcolors(im, maxcolors=num)# returns a list of tuples (count, colour)

michaelk · 02-06-2024, 02:45 AM

To truncate or create empty file add before loop

: > /path/to/colours.txt

MadeInGermany · 02-07-2024, 04:16 AM

Each >> is an open+append+write+close
The following is smarter and also allows to overwrite with a >

Code:

path2files="/home/pedro/Downloads/"
for f in "$path2files"*.jpg
do
  echo "$f"
  colours=$(identify -format %k "$f")
  echo "$colours"
  echo "$f:$colours" >&3
done 3> home/pedro/Downloads/colours.txt

The loop block gets a descriptor 3 that is directed to the output file.
The output file is opened when the loop starts, and is closed when the loop ends.

BTW
echo "$colours" >&2
would write to descriptor 2 that is by default directed to stderr.
And
echo "$colours"
is like
echo "$colours" >&1
(descriptor 1, directed to stdout, is the default)

Pedroski · 02-17-2024, 12:48 PM

Sorry, only just saw your reply!

Thanks!

Your script works great, just a / missing before file path, no biggie, bash complained, I could see the problem, fixed it!