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Re: how to detect if a jpeg file is progressive or not

H.S.(hs.samix@gmail.com) is reported to have said:
> Hi Wayne,
> I tried your way and converted all the image with quality 25. You are
> right, I couldn't notice any perceptual difference at normal size. The
> different is noticable only if you magnify the image.
> I had a total of 14 images of size 2272x1704 (taken by a 4 megapixel
> digital camera). I reduced them in size (682x511 pixels; or to 30%) and
> their quality (to 25). The reduced size images were taking a total of
> 2.7 MB at default quality. But by using quality 25, the disk space usage
> reduced to 0.608 MB! This is a great improvement. (I am still getting
> progressive jpegs as the output.)

Glad to hear it helped.  I have added the '-interlace plane' to my
script, thanks to you, and am getting my images down a bit more as

> Here is the command I used to do the conversion (it is a one long line):
> $> for f in *.jpg; do echo "$f"; bn=`basename "$f" .jpg`; convert
> -resize 30% -quality 25 -interlace plane "$f" ${bn}-small.jpg; done

Very nice.  I used to do the convert to selected images in my Digikam
album's but had to go to a script since the last Digikam upgrade.  It
seems the batch processing was left out in this version.  

I'm glad you posted your query.  I have learned something new again
this week!  DU never fails!

Best Regards


At the source of every error which is blamed on the computer you will
find at least two human errors, including the error of blaming it on
the computer.

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