Find valid wallpapers by resolution

XeroXer · 11-13-2009, 03:09 AM

Hi all!

Was hoping that someone knew any software or maybe a script that can validate a wallpaper resolution and sort out the valid images.
I made a bash script that calculated the image aspect ratio and checked that against 4:3 and 16:9.
But as I noticed there are a lot of small resolutions that still validate, and a lot of large ones that don't.
Instead of adding them all and checking for a minimum width/height I thought I could ask here.

The problem is that I have a folder filled with images that claim to be wallpapers but I know some of them are not, since some have a higher height than width and some just have a very strange resolution.

So a software or a script that can validate the resolution or aspect ratio against valid ones would be great.
Hope someone can help...

jswetzen · 11-13-2009, 04:29 AM

I'd go for a bash script, it seems simple enough. If you post your script here, I could have a look at it.

jschiwal · 11-13-2009, 04:44 AM

Mediainfo will report the resolution of pictures and videos. You can use sed or awk to extract the info you need and assign the result to a variable.

The ImageMagic package includes the `identify' command which supplies information on images that would be easier to extract.

Code:

> identify work/roseb.eps
work/roseb.eps PS 612x792 612x792+0+0 16-bit DirectClass 9.55kb

> identify work/roseb.eps | 
sed 's/.* [A-Z][A-Z]* \([[:digit:]][[:digit:]]*\)x\([[:digit:]][[:digit:]]*\) .*/width=\1\nheight=\2\n/'
width=612
height=792

> eval $(identify work/roseb.eps | sed 's/.* [A-Z][A-Z]* \([[:digit:]][[:digit:]]*\)x\([[:digit:]][[:digit:]]*\) .*/width=\1\nheight=\2\n/')
> echo $width
612

Using something like this, it would make a lot of sense to put the parsing code in a bash function.

It would hide the dirty details in your main script. You could have one function width() and another one height() and then use the functions in a numerical test. This would make your main code very readable.

XeroXer · 11-13-2009, 06:34 AM

This is how my bash script looks today. Not much but it seems to do the trick, but as said before I need a better working check.

Code:

#!/bin/bash
find . -type f -name '*.jpg' | sort | while read file
do
    set -- $(identify -format "%w %h" -quiet "$file")
    calculation=$(echo "scale=10; $1 / $2" | bc -l)
    if ! [ $calculation == "1.3333333333" -o $calculation == "1.7777777777" ]
    then
        echo "File '${file}' has the wrong aspect ratio (${1}x${2} - ${calculation}).";
    fi
done

jswetzen · 11-15-2009, 11:12 AM

Can you find anything special with the files that fail? It would be interesting seeing the height and width values for the files that fail, because as long as the output from identify is correct your script seems quite solid.

XeroXer · 11-15-2009, 01:26 PM

I added support for some other aspect ratios. This script seems to work just as I want...

Code:

#!/bin/bash
# 4:3 - 1.3333333333
# 5:4 - 1.2500000000
# 16:9 - 1.7777777777
# 16:10 - 1.6000000000
find . -type f -name '*.jpg' | sort | while read file
do
    set -- $(identify -format "%w %h" -quiet "$file")
    calculation=$(echo "scale=10; $1 / $2" | bc -l)
    if ! [ $calculation == "1.3333333333" -o $calculation == "1.2500000000" -o $calculation == "1.7777777777" -o $calculation == "1.6000000000" ]
    then
        echo "File '${file}' has the wrong aspect ratio (${1}x${2} - ${calculation}).";
    fi
done

SaintDanBert · 11-15-2009, 02:21 PM

Quote:

Originally Posted by XeroXer

I added support for some other aspect ratios. This script seems to work just as I want...

Code:

#!/bin/bash
# 4:3 - 1.3333333333
# 5:4 - 1.2500000000
# 16:9 - 1.7777777777
# 16:10 - 1.6000000000
...
    if ! [ $calculation == "1.3333333333" -o 
        $calculation == "1.2500000000" -o 
        $calculation == "1.7777777777" -o 
        $calculation == "1.6000000000" ]
    then
        echo "File '${file}' has the wrong aspect ratio (${1}x${2} - ${calculation}).";
    fi
...

Consider something like this:

Code:

...
    FOUR_BY_THREE="1.3333333333"
    FIVE_BY_FOUR="1.2500000000"
    WIDE_BY_NINE="1.7777777777"
    WIDE_BY_TEN="1.6000000000"
...
    calculation=$( ... )
    case "$calculation" in
    "$FOUR_BY_THREE")
    "$FIVE_BY_FOUR")
    "$WIDE_BY_NINE")
    "$WIDE_BY_TEN")
        echo "... do this for good ratios"
        ;;
    *)
        echo "??? do this for wrong ratios"
        ;;
    esac
...

It makes the code more readable, easier to maintain, and so on.

Sorry, I'm not a shell programming maven so my code describes an intention not a working implementation.

~~~ 0;-Dan