[Paraview] png image file size - screenshot vs animation

[Stief, Alexander]

This does not fit my observation.
Saving as a screenshot, I get a reasonably small png file size.
Saving the same scene as an animation instead, I get huge png files instead regardless of the image content.

I tried again with a plain white scene and a resolution of 6428x3764
File size using save screenshot (image quality 100): 85.2KiB
File size using save animation (image quality 100): 69.3Mib
File size using save animation (image quality 80): 327.2Kib



Alex,

In 5.4, save screenshot didn't compress the images at all. This was
done simply to improve the performance since compression took
considerable amount of time for larger images. However, it's been
changed in 5.5 to a more sensible default for both animations and save
screenshots.

Also note, with PNG compression doesn't affect image quality since
it's always lossless.

Utkarsh

On Wed, Mar 28, 2018 at 7:20 AM, Stief, Alexander
<Alexander.Stief at hs-aalen.de> wrote:
> Hi,
>
> PV version is 5.4.1
> when making a png screenshot in PV with a resolution of 3840x2160, the file
> size I get with default settings is ~1.4MB. This is due to the fact that
> around 80% of the image are plain white space. So far, so normal.
> However, when I create an animation and export to png images with the exact
> same default settings for image quality, the image file size for the exact
> same scene is ~28MB.
> Only when I dial down the image quality manually to around 60 the file size
> becomes similar to the png file from the screenshot. And the image quality
> is not visibly worse than with 100% setting.
> This must be some kind of bug, I never had this issue with previous
> versions.
>
> tl;dr: png image file size differs greatly between screenshot and animation
> with the exact same default settings.
>
> Regards
> Alex
>
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