[Solved] PNG Crop Grows Drastically

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comccoy
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[Solved] PNG Crop Grows Drastically

Post by comccoy »

I have a bunch of portraits I have been scanning at 1200x1200 ppi, 24bit, 16.7 million colors and saving as PNG (Epson Expression v600). As the masking for the scan is a bit inaccurate I pad them slightly and crop them post scan. I am finding that the files are growing drastically when I crop (or any adjustment) and save and it looks like Graphicconverter is removing the compression and forcing them from the 1:3 or 1:2 compression I started with to 1:1.

How can I keep or redo the lossless PNG compression?

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forum_adm
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Re: PNG Crop Grows Drastically

Post by forum_adm »

Please check the PNG save as options.
Screen Shot 2020-05-23 at 11.36.jpg
Screen Shot 2020-05-23 at 11.36.jpg (110.75 KiB) Viewed 40 times
What did you select?

Also, did you maybe save with a custom icon in the resource fork?

Thorsten

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Re: PNG Crop Grows Drastically

Post by forum_adm »

Please e-mail the file zipped to support@lemkesoft.de if you still have problems with the file size.

comccoy
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Re: PNG Crop Grows Drastically

Post by comccoy »

Here are my save settings, the information on an original scan and a cropped scan that I would think would be slightly smaller in size from image size reduction. The compression went to 1:2 from 1:3 and the size jumped from 60.84MB to 85.36MB. Maybe that is a huge preview? I cannot email these files due to the size but I can upload somewhere or gather any other info that's useful.
Screen Shot 2020-05-23 at 7.44.14 PM.png
Screen Shot 2020-05-23 at 7.44.14 PM.png (199.2 KiB) Viewed 28 times
Screen Shot 2020-05-23 at 7.44.36 PM.png
Screen Shot 2020-05-23 at 7.44.36 PM.png (243.16 KiB) Viewed 28 times
Screen Shot 2020-05-23 at 7.44.56 PM.png
Screen Shot 2020-05-23 at 7.44.56 PM.png (240.44 KiB) Viewed 28 times

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forum_adm
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Re: PNG Crop Grows Drastically

Post by forum_adm »

The filter None cause the size change.

You get the best results with automatic. But that is very slow. Because it tries for all image lines each filter and compares the results.

Thorsten

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Re: PNG Crop Grows Drastically

Post by forum_adm »

Please download the latest BETA:
http://www.lemkesoft.org/beta.html

and select as filter the new Dynamic.

That is much faster than the old Automatic and should create a smaller PNG.

Thorsten
Screen Shot 2020-05-24 at 09.01.jpg
Screen Shot 2020-05-24 at 09.01.jpg (119.48 KiB) Viewed 23 times

comccoy
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Re: PNG Crop Grows Drastically

Post by comccoy »

So my original was 60.8MB. The None filter produced an 85.4MB file. With Dynamic it is 64.3MB. Thank you for your help!

For my mind I have a hard time understanding how I take a 51.5 megapixel image, crop it and reduce the actual number of pixels and end up with a larger file size. I think I just don't understand the algorithms that "build" what is displayed on the screen.

I tried Preview and it cropped up to 69.6MB.

Thank you so much for your help. I will work with the beta for now. :D