PNG export quality slider 1 - 10

[D.T. Nethery]

My Feature Improvement request is that the slider which sets the compression ratio (a sliding scale from 1 - 10 ) for PNG export would display how large the resulting PNG files will be in KB.
When moving the slider the actual frame size value in KB (for the current frame) will be displayed as you move the slider. I believe this feature was requested and "To-Do Listed" in 2014 , but was never implemented , so I am resubmitting this as a new request.

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Some further explanation of the reason for requesting this improvement to the PNG export :

It is my observation that there is generally some confusion for new users (or even long-time uses) over the 1 - 10 compression ratio sliding scale when exporting images as PNGs.

TVPaint_PNG_Export_Compression_Ratio.png (42.22 KiB) Viewed 5060 times

In my experience speaking with users who are confused by this sliding 1 - 10 scale, the confusion is usually: "what do the numbers 1 - 10 represent ?"

I think that most people tend to assume 1 means lowest image quality and that 10 means the highest image quality.

In fact, the 1 - 10 scale has nothing to do with the image quality. It is about the time it takes to complete the export and the file size of the exported PNG files . I don't believe this is explained anywhere in the User Guide (perhaps it is explained in the soon-to-be-released new User Guide , but not in the current User Guide).

Setting the export compression ratio to 1 means that the speed of the PNG image sequence export will be FAST , but the file size of the exported PNGs will be much LARGER.
If the export compression ratio is set to 10 the export time is SLOWER , but the file sizes will be much SMALLER. The image quality is not impacted by choosing a compression ratio of 1 or 10 or any number between 1 and 10.

For example, as a test I exported an Image Sequence of 24 drawings. With the compression ratio set to 1 the export took 6 seconds. The total size of the PNG files = 200 MB.
With compression level set to 10 the export took 21 seconds. But in this case the total size of the PNG files = 3.4 MB. That's a huge difference in total file size.

At the very least an explanation of the compression ratio scale 1 - 10 when exporting PNGs needs to be explained clearly in the User Guide. It would be nice if the Tool Tip explained:

"NOTE that the image quality of the exported PNGs is not affected
by the compression value, only the time it takes to export and the
final file size of the exported PNGs.
Compression value of 1 = Fastest export time, larger file size .
Compression value of 10 = Slowest export time, smaller file size."

Even better would be when moving the slider the actual frame size value in KB (for the current frame) will be displayed as you move the slider.

File size displayed with compression sliding scale.png (29.14 KiB) Viewed 5060 times

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[slowtiger]

Hm, I doubt that this will work - TVP doesn't know about file size before the actual image is analysed for conversion. And it will not work with a whole sequence of images. At the very least I expcct that this calculation will take as long as saving those images anyway.

[D.T. Nethery]

It might not work. But at one time it was "to-do listed" , so I'm asking again.

I think what I'm envisioning is something like this slider in Photoshop. When you adjust the sliding scale from 12 (Maximum) to 1 (Low) it estimates the file size.



Although in Photoshop this is for JPG .

For PNG Photoshop has three choices: Smallest File Size (slowest saving), Medium File Size (medium saving), Largest File Size (fastest saving),
but doesn't display the estimated file size.

Screen Shot 2022-07-10 at 1.16.42 PM.png (21.99 KiB) Viewed 5046 times

So maybe not possible for it to estimate the file size of PNGs based on the export compression ratio chosen ?


At any rate, the Tool Tip and the User Guide should clarify the function of the PNG compression when setting the value to 1 or to 10 or any number between 1 and 10 .
I was reminded of this again recently when I read a comment posted on another forum where someone asked: "Why are the png files TVPaint spits out so incredibly massive?"
(it's because he had the PNG export compression ratio set to 1 which created large file sizes. He didn't understand that changing the compression to 5 or 10 would significantly reduce the file size of the exported PNGs).

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For some context , here was one of the previous discussions: https://forum.tvpaint.com/viewtopic.php?p=70024#p70024

Note Eric M's response was: "Do you really care about file size ? (not that we won't add it, it should be pretty easy, at least for image file formats)"

When he wrote: "not that we won't add it , it should be pretty easy" , I took that to mean it was possible. But this seems to be one of those feature requests that fell through the cracks over the years, so I'm bringing it up again .



.

[Joost]

My Feature Improvement request is that the slider which sets the compression ratio (a sliding scale from 1 - 10 ) for PNG export would display how large the resulting PNG files will be in KB.
When moving the slider the actual frame size value in KB (for the current frame) will be displayed as you move the slider. I believe this feature was requested and "To-Do Listed" in 2014 , but was never implemented , so I am resubmitting this as a new request.

--------

Some further explanation of the reason for requesting this improvement to the PNG export :

It is my observation that there is generally some confusion for new users (or even long-time uses) over the 1 - 10 compression ratio sliding scale when exporting images as PNGs.


TVPaint_PNG_Export_Compression_Ratio.png


In my experience speaking with users who are confused by this sliding 1 - 10 scale, the confusion is usually: "what do the numbers 1 - 10 represent ?"

I think that most people tend to assume 1 means lowest image quality and that 10 means the highest image quality.

In fact, the 1 - 10 scale has nothing to do with the image quality. It is about the time it takes to complete the export and the file size of the exported PNG files . I don't believe this is explained anywhere in the User Guide (perhaps it is explained in the soon-to-be-released new User Guide , but not in the current User Guide).

Setting the export compression ratio to 1 means that the speed of the PNG image sequence export will be FAST , but the file size of the exported PNGs will be much LARGER.
If the export compression ratio is set to 10 the export time is SLOWER , but the file sizes will be much SMALLER. The image quality is not impacted by choosing a compression ratio of 1 or 10 or any number between 1 and 10.

For example, as a test I exported an Image Sequence of 24 drawings. With the compression ratio set to 1 the export took 6 seconds. The total size of the PNG files = 200 MB.
With compression level set to 10 the export took 21 seconds. But in this case the total size of the PNG files = 3.4 MB. That's a huge difference in total file size.

At the very least an explanation of the compression ratio scale 1 - 10 when exporting PNGs needs to be explained clearly in the User Guide. It would be nice if the Tool Tip explained:

"NOTE that the image quality of the exported PNGs is not affected
by the compression value, only the time it takes to export and the
final file size of the exported PNGs.
Compression value of 1 = Fastest export time, larger file size .
Compression value of 10 = Slowest export time, smaller file size."

Even better would be when moving the slider the actual frame size value in KB (for the current frame) will be displayed as you move the slider.


File size displayed with compression sliding scale.png




.

+1
This is indeed always really confusing. Is 10 the best quality or the worst quality?
After years of using TVPaint I still don't know the answer

[D.T. Nethery]

+1
This is indeed always really confusing. Is 10 the best quality or the worst quality?
After years of using TVPaint I still don't know the answer

Yes, it confused me for a long time, too. In my experience training new users or even working with long-time users of TVPaint it is still a source of confusion.

What should be made clear in the User Manual and the Tool Tips is that when exporting PNGs the sliding scale from 1 - 10 for compression ratio has no effect on the final image quality of the exported PNGs , but is related to the file size (1 = LARGER file size ; 10 = SMALLER file size) and how fast the export action will be performed (1 = Faster export (but larger file size) ; 10 = Slower export (but smaller file size)



Photoshop offers only three options for exporting PNGs : Large, Medium, Small , but it clearly explains what the options mean:

Smallest File Size (Slowest saving)
Medium File Size (Medium saving)
Large File Size (Fastest Saving)

PNG Export from PS.png (21.99 KiB) Viewed 4956 times

It would be an improvement in TVPaint for the Tool Tip to say something like this:

"NOTE that the image quality of the exported PNG file is not changed
by the compression value, only the time it takes to export and the
final file size of the exported PNGs.
Compression value of 1 = Fastest export time, larger file size .
Compression value of 5 = Medium export time, medium file size.
Compression value of 10 = Slowest export time, smaller file size."


Although in practical use I notice there is a minimal difference between a compression value of 5 and compression value of 10. For example, I just did a test exporting a full color image. At a compression ratio value of 5 = 1.7 MB ; at compression value of 10 = 1.6 MB . Not much difference.

By comparison, the same image exported with compression ratio value of 1 = 4.5 MB (2.8x larger than compression value of 10 . With multiple images in an animation sequence that would be a significant size difference.)


.

[Joost]

+1
This is indeed always really confusing. Is 10 the best quality or the worst quality?
After years of using TVPaint I still don't know the answer

Yes, it confused me for a long time, too. In my experience training new users or even working with long-time users of TVPaint it is still a source of confusion.

What should be made clear in the User Manual and the Tool Tips is that when exporting PNGs the sliding scale from 1 - 10 for compression ratio has no effect on the final image quality of the exported PNGs , but is related to the file size (1 = LARGER file size ; 10 = SMALLER file size) and how fast the export action will be performed (1 = Faster export (but larger file size) ; 10 = Slower export (but smaller file size)



Photoshop offers only three options for exporting PNGs : Large, Medium, Small , but it clearly explains what the options mean:

Smallest File Size (Slowest saving)
Medium File Size (Medium saving)
Large File Size (Fastest Saving)


PNG Export from PS.png



It would be an improvement in TVPaint for the Tool Tip to say something like this:

"NOTE that the image quality of the exported PNG file is not changed
by the compression value, only the time it takes to export and the
final file size of the exported PNGs.
Compression value of 1 = Fastest export time, larger file size .
Compression value of 5 = Medium export time, medium file size.
Compression value of 10 = Slowest export time, smaller file size."


Although in practical use I notice there is a minimal difference between a compression value of 5 and compression value of 10. For example, I just did a test exporting a full color image. At a compression ratio value of 5 = 1.7 MB ; at compression value of 10 = 1.6 MB . Not much difference.

By comparison, the same image exported with compression ratio value of 1 = 4.5 MB (2.8x larger than compression value of 10 . With multiple images in an animation sequence that would be a significant size difference.)


.

Ah, I never knew that what you described was wat this slider meant! It's an eye opener. I always wondered why my PNG files where saved so slowly! LOL
I always thought 10 is maximum quality, but it's the tiniest file size = slow saving. Interesting... I will decently change the standard setting to 1 now

[Matthieu]

I agree things should be more clear regarding the PNG compression settings. The User Guide will be updated accordingly, thanks for pointing this out!

[D.T. Nethery]

Ah, I never knew that what you described was wat this slider meant! It's an eye opener. I always wondered why my PNG files where saved so slowly! LOL

I always thought 10 is maximum quality, but it's the tiniest file size = slow saving. Interesting... I will decently change the standard setting to 1 now

Keep in mind if you change the PNG compression ratio to 1 your PNG files will be much larger. If you have a fast computer and lots of storage space, this may not be an issue, but I prefer to have the PNGs be smaller files if possible. In experimenting with the different ratios , I've arrived at keeping mine almost always set to 5. File sizes are not much larger than using 10 , but it does seem to export a bit more quickly than 10.

[Joost]

Ah, I never knew that what you described was wat this slider meant! It's an eye opener. I always wondered why my PNG files where saved so slowly! LOL

I always thought 10 is maximum quality, but it's the tiniest file size = slow saving. Interesting... I will decently change the standard setting to 1 now

Keep in mind if you change the PNG compression ratio to 1 your PNG files will be much larger. If you have a fast computer and lots of storage space, this may not be an issue, but I prefer to have the PNGs be smaller files if possible. In experimenting with the different ratios , I've arrived at keeping mine almost always set to 5. File sizes are not much larger than using 10 , but it does seem to export a bit more quickly than 10.

Thanks for the info! I definitely will try to set it to 5.... (1 was indeed too big)