Mac – way to find only progressive jpegs on Mac using Adobe CS or other apps

jpegmac

To put my work up on my website, I initially collected some images and converted them to progressive jpegs. But later I went in and added more. I now can't tell simply by file size which ones are progressive and which ones are not. Is there a specific property in the file info in Finder, Path Finder or Bridge that can tell me which ones are progressive?

Better still, can I do a search for only progressive jpg files?

Best Answer

I found a simple tool that tests whether a JPEG is progressive. However, you have to test them one by one. It's probably not as automated as you were looking for, but it might be interesting for someone else having the same issue.

It uses HTML5 new features and JS, so it should be cross platform.

The tool: http://techslides.com/demos/progressive-test.html

Source: http://techslides.com/detecting-progressive-jpeg/

Related Solutions

JPEG Repair – Suggestions on How to Fix Corrupt Files

Your DSC02322-bad.jpg file is 2178036 nul bytes (i.e. 2178036 single byte zeros):

$ hexdump DSC02322-bad.jpg 
0000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
*
0213bf0

Your DSC02322-good.jpg file is 2178036 bytes of JPEG data. There's nothing to repair in DSC02322-bad.jpg as there's nothing left.

By the way, the file command says "data" when it doesn't know what else to say.

Automating the choice between JPEG and PNG with a script

Edit: Fixed some issues with the original script. Added an alternative one based on Marcks Thomas' proposition.

Edit 2: Updated cutoff values based on a number of test runs. I am still not sure how to estimate file sizes for greyscale images. If you are working with a large number of images outside of RGB colour schemes you might want to implement the first script as a fallback mode to the second one.

Edit 3: Added optipng integration. This optimizes PNG file sizes without any quality loss. See here for more information. Some smaller improvements.

Version 0.1

Important note: This script is deprecated. Newer versions are far more efficient.

Alright, my question might have been slightly too localized, so I put some time into it and compiled the script myself:

#!/bin/bash

# AUTHOR:   (c) MHC (http://askubuntu.com/users/81372/mhc)
# NAME:     Intelliconvert 0.1
# DESCRIPTION:  A script to automate and optimize the choice between different image formats.
# LICENSE:  GNU GPL v3 (http://www.gnu.org/licenses/gpl.html)
# REQUIREMENTS:  Imagemagick

ORIGINAL="$1"

###Filetype check###

MIME=$(file -ib "$ORIGINAL")

if [ "$MIME" = "image/png; charset=binary" ]
  then
    echo "PNG Mode"

###Variables###

      ##Original Image##
    FILENAME=$(basename "$ORIGINAL")
    PARENTDIR=$(dirname "$ORIGINAL")
        SUBFOLDER=$(echo "$PARENTDIR" | cut -d"/" -f10-)
    ORIGARCHIVE="~/ORIG"

      ##Converted Image##
    TEMPDIR="/tmp/imgcomp"
    CONVERTED="$TEMPDIR/$FILENAME.jpg"

      ##Image comparison##
    DIFFLO="50"
    DIFFHI="75"
    CUTOFF="1000000"

      ##DEBUG
    echo "#### SETTINGS ####"
    echo "Filepath to original = $ORIGINAL"
    echo "Filename= $FILENAME"
    echo "Parent directory = $PARENTDIR"
    echo "Archive directory = $ORIGARCHIVE"
    echo "Temporary directory = $TEMPDIR"
    echo "Filepath to converted image = $CONVERTED"
    echo "Low cut-off = $DIFFLO"
    echo "High cut-off = $DIFFHI"

###Conversion###

    convert -quality 92 -flatten -background white "$ORIGINAL" "$CONVERTED"

###Comparison###

    F1=$(stat -c%s "$ORIGINAL" )
    F2=$(stat -c%s "$CONVERTED" )
    FQ=$(echo "($F2*100/$F1)" | bc)

      #Depending on filesize we use a different Cut-off#
    if [ "$F1" -ge "$CUTOFF" ]
      then
        DIFF="$DIFFHI"
      else  
        DIFF="$DIFFLO"
    fi

      ##DEBUG
    echo "### COMPARISON ###"
    echo "Filesize original = $F1 Bytes"
    echo "Filesize converted = $F2 Bytes"
    echo "Chosen cut-off = $DIFF %"
    echo "Actual Ratio = $FQ %"


    if [ "$FQ" -le "$DIFF" ]
      then
           echo "JPEG is more efficient, converting..."
           mv -v "$CONVERTED" "$PARENTDIR"
               mkdir -p "$ORIGARCHIVE/$SUBFOLDER"
           mv -v "$ORIGINAL" "$ORIGARCHIVE/$SUBFOLDER"
      else
           echo "PNG is fine, exiting."
           rm -v "$CONVERTED"
    fi


  else
    echo "File does not exist or unknown MIME type, exiting."

fi

The script works great in combination with Watcher.

This is my first proper script, so there might be some unresolved bugs and issues I just didn't see. Feel free to use it for yourself and improve it. If you do so, I'd appreciate it if you could leave a comment here, so that I can learn from it.

Version 0.2.1

A more efficient way of finding the right format can be achieved by comparing the original's file size to its estimated size as an uncompressed image:

#!/bin/bash

# AUTHOR:   (c) MHC (http://askubuntu.com/users/81372/mhc)
# NAME:     Intelliconvert 0.2.1
# DESCRIPTION:  A script to automate and optimize the choice between different image formats.
# LICENSE:  GNU GPL v3 (http://www.gnu.org/licenses/gpl.html)
# REQUIREMENTS:  Imagemagick, Optipng

################ Filetype Check#################

MIME=$(file -ib "$1")

if [ "$MIME" = "image/png; charset=binary" ]
  then
    echo "###PNG Mode###"

####################Settings####################

##Folders##
ORIGARCHIVE="~/ORIG"

##Comparison##
DIFFLO="25"
DIFFHI="20"
CUTOFF="1000000"

################################################

###Variables###

ORIGINAL="$1"
FILENAME=$(basename "$ORIGINAL")
PARENTDIR=$(dirname "$ORIGINAL")
SUBFOLDER=$(echo "$PARENTDIR" | cut -d"/" -f10-)
CONVERTED="$PARENTDIR/$FILENAME.jpg"

#DEBUG#
    echo "###SETTINGS###"
    echo "Filepath to original = $ORIGINAL"
    echo "Filename= $FILENAME"
    echo "Parent directory = $PARENTDIR"
    echo "Archive directory = $ORIGARCHIVE"
    echo "Filepath to converted image = $CONVERTED"
    echo "Low cut-off = $DIFFLO"
    echo "High cut-off = $DIFFHI"


###Image data###

        WIDTH=$(identify -format "%w" "$ORIGINAL")
        HEIGHT=$(identify -format "%h" "$ORIGINAL")
        ZBIT=$(identify -format "%z" "$ORIGINAL")
        COL=$(identify -format "%[colorspace]" "$ORIGINAL")
        F1=$(stat -c%s "$ORIGINAL")

        if [ "$COL" = "RGB" ]
          then
              CHANN="3"
          else
              CHANN="1"
        fi


###Cutoff setting###

    if [ "$F1" -ge "$CUTOFF" ]
      then
        DIFF="$DIFFHI"
      else  
        DIFF="$DIFFLO"
    fi


###Calculations on uncompressed image###

        BMPSIZE=$(echo "($WIDTH*$HEIGHT*$ZBIT*$CHANN/8)" | bc)
        FR=$(echo "($F1*100/$BMPSIZE)" | bc)

#DEBUG#

        echo "###IMAGE DATA###"
        echo "Image Dimensions = $WIDTH x $HEIGHT"
        echo "Colour Depth = $ZBIT"
        echo "Colour Profile = $COL"
        echo "Channels = $CHANN"
        echo "Estimated uncompressed size = $BMPSIZE"
        echo "Actual file size = $F1"
        echo "Estimated size ratio = $FR %"
        echo "Cutoff at $DIFF %"

###Backup###

        echo "###BACKUP###"
        mkdir -p "$ORIGARCHIVE/$SUBFOLDER"  #keep the original folder structure
        cp -v "$ORIGINAL" "$ORIGARCHIVE/$SUBFOLDER"
        echo ""

###Comparison###

    if [ "$FR" -ge "$DIFF" ]
      then
          echo "JPEG is more efficient, converting..."
          convert -quality 92 -flatten -background white "$ORIGINAL" "$CONVERTED"
              echo "Done."
          echo "Cleaning up..."
          rm -v "$ORIGINAL"
      else
          echo "PNG is fine, passing over to optipng."
              echo "Optimizing..."
              optipng "$ORIGINAL"
              echo "Done."
    fi

################ Filetype Check#################

  else
    echo "File does not exist or unknown MIME type, exiting."

fi

Props to @Marcks Thomas for the great idea.

Best Answer

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