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Scaling down JPG produces abnormally big file.


dipmicro
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Hello everyone,

I use JPG for product picutres, manually create thumbnails in Paint.NET. Scale down the original to 1024x768, fill the background and replace with #FFFFFF. Usual size is around 80-120k.

Then I create a small version of 320x240. The file produced by Paint.NET is around 45-55k. This is big! I tried to load and resave with paint, but did not help. So I selected entire picture and created new 320x240 one and pasted there. Then saved with original name and voila - 8k!

This is not a random fluke very repeatable. Perhaps its something wrong with JPG generated with my Nikon Coolpix L4, I don;t know. I even went and got MacroMaker so I could automate this with Paint.NET for hundreeds of pictures.

Does anyone have an explanation on what's going on? Can JPG store an old version of picture?

Thanks

Roman

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Yes, and another interesting point that may be related is that when in Save As, the thumbnails of pictures are original unedited photos as opposed to edited versions with removed background.

On the screenshot in the attachment its visible that all the pictures have still background although this background has been removed in 1024x768 version and 320x240 version never had this background, because it was scaled down edited 1024.

Yet all the images excluding the one that was copied and pasted into new image (test.jpg) show as thumbnails with background even after deleting thumbs.db.

That's why I was asking if JPG could carry the second image like ICO or GIF ... and where Windows Explorer gets this old version from. That would also explain the abnormal size of these JPGs.

I just did yet another experiment and moved the 1024 version to another directory. The thumbnail had background. So I opened it in Paint.NET, selected entire image and pasted into brand new 1024x768 image and saved with 60% quality (that's what I always use for web). The result was 51k.

The original file saved with 60% quality is 89k and is attached to this post. Open with Paint.NET, copy & paste into new image and save with 60% quality, will be 51k.

11080_2a2a0bdb43cbabe35b61c1aefd8884a0

11080_5c34cf92c6c6b78e18cd43b0006f4b36

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Metadata accounts for a large percentage of the filesize of small files. A metadata editor is on the roadmap for a future release, I believe.

 

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Amy: But how did it end up in there?
The Doctor: You know fairy tales. A good wizard tricked it.
River Song: I hate good wizards in fairy tales; they always turn out to be him.

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  • 2 weeks later...
Open your jpg image and press the following:

Ctrl-A (Select all)

Ctrl-C (Copy)

Ctrl-Alt-V (Paste to a new image)

Ctrl-S (Save)

That will strip out most of the metadata from your image.

So... doing that will get rid of unneeded data and therefore reduce the filesize? I suck at anything involving data, all I know is my bytes and bits.

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Open your jpg image and press the following:

Ctrl-A (Select all)

Ctrl-C (Copy)

Ctrl-Alt-V (Paste to a new image)

Ctrl-S (Save)

That will strip out most of the metadata from your image.

Of course ... that's the 2nd paragraph of my original post. However, the other JPG editor can get the pic even smaller without funny workaround.

So for the moment I am editing the pics in Paint.NET but final rescaling is done in IV.

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