[Paraview] png image file size - screenshot vs animation

[Utkarsh Ayachit]

I may have spoken the other way around. In any case, just hold on till
5.5 is out and this will be addressed.

Utkarsh

On Wed, Mar 28, 2018 at 1:13 PM, Stief, Alexander
<Alexander.Stief at hs-aalen.de> wrote:
> 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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