Resize png 8 bits

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den1a
Posts: 3
Joined: Sat May 14, 2022 6:04 am

Resize png 8 bits

Post by den1a »

Hello. I want to crop the photo, but I get a poor quality photo. Please tell me how to fix the problem

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nconvert -overwrite -resize 1500 1200 -ratio -rflag decr image.png
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JeanMich
Posts: 2
Joined: Mon May 16, 2022 4:34 pm

Re: Resize png 8 bits

Post by JeanMich »

Hello,
I don't quite get it : you are not cropping anything here.

Whatever, I'm no expert but I'd try to add

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-out png -clevel 9  
to specify the output file format (png) and the compression level.

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 -overwrite -out png -clevel 9  -ratio -resize 1500 1200 -rflag decr 
It's giving me an image with the correct colors.
If you have different images from different sources, I'd add also something to deal with transparency, alpha chanel, metadata and so on to make smaller files.
cday
XnThusiast
Posts: 3258
Joined: Sun Apr 29, 2012 9:45 am
Location: Cheltenham, U.K.

Re: Resize png 8 bits

Post by cday »

The GUI software XnConvert, with it's Actions Preview, can provide an easy way to test different settings, but testing with 1.95 I haven't managed to obtain the desired result, no breakup of the image though.
den1a
Posts: 3
Joined: Sat May 14, 2022 6:04 am

Re: Resize png 8 bits

Post by den1a »

In my case, the problem was solved by adding a parameter -rtype quick

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nconvert -overwrite -resize 1500 1200 -ratio -rflag decr -rtype quick image.png
cday
XnThusiast
Posts: 3258
Joined: Sun Apr 29, 2012 9:45 am
Location: Cheltenham, U.K.

Re: Resize png 8 bits

Post by cday »

den1a wrote: Tue May 17, 2022 5:08 am In my case, the problem was solved by adding a parameter -rtype quick

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nconvert -overwrite -resize 1500 1200 -ratio -rflag decr -rtype quick image.png
Interesting...

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-rtype        : Type of resampling
          quick    : Quick resize
          linear   : Bi-linear (linear)
          hermite  : Hermite
          gaussian : Gaussian
          bell     : Bell
          bspline  : Bspline
          mitchell : Mitchell
          lanczos  : Lanczos
den1a
Posts: 3
Joined: Sat May 14, 2022 6:04 am

Re: Resize png 8 bits

Post by den1a »

Unusual, but it works :)
Thank you for responding!