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PNG Compression
"2. Regarding PNG - this is problematic because it doesn't support multiple pages in one file"
Well, this is not entirely true. While the original PNG format may only allow one image, there are two specifications which are more than quite mature that allow for multiple images in one PNG;
- http://animatedpng.com/index.php/about/
and
- http://www.libpng.org/pub/mng/
both have open source libraries and open specifications availalable to them.
I think it would greatly enhance an otherwise excellent product to have this superior compression available.
Well, this is not entirely true. While the original PNG format may only allow one image, there are two specifications which are more than quite mature that allow for multiple images in one PNG;
- http://animatedpng.com/index.php/about/
and
- http://www.libpng.org/pub/mng/
both have open source libraries and open specifications availalable to them.
I think it would greatly enhance an otherwise excellent product to have this superior compression available.
I’m glad the developers are willing to discuss
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Inappropriate?Interesting links.
The first one seems more oriented to animated image files.
The second link seems to have support for multiple images (the MNG format).
The problem with using the MNG format will be
1. Most of our users feel more confident with a format that they know (all are afraid from proprietary formats) and can open with their default Windows viewer (Vista/XP or other). As far as I know they do not support the MNG format.
2. Creating the files maybe easy, but I am not sure how easy will it be to display them in our viewer. (We can always convert them in memory, but I am afraid of performance issues).
Shimon
I’m happy to have a great professional discussion
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Inappropriate?Well, animated image files, just as GIF's are nothing more than a sequence of images, with the extra provision of 'delta' information (so you do not have to store more than necessary).
All 'animated' formats can be shown as multiple images
On that note, grayscale images could be GIF's...
The APNG format is supported natively by Firefox and Opera and there is a freeware viewer for a lot of platforms:
http://pagesperso-orange.fr/pierre.g/...
That would be no different than what you are doing now with the jpeg compression.
(also, check the SDK, that might be of help to you as well)
As for performance, I think that will be alright; I have made a couple of comicbook-readers for handhelds, and converting the decoded images never was a cpu-hog.
You could make it an option; store in APNG or TIFF, that way people can decide for themselves.
I was unable to reproduce the weird size I had earlier.
I’m that the developers react so fast
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Inappropriate?We have built 42Tags using C# .NET and we will look on library supporting MNG.
If you know one we would like to hear...
For any issue don't hesitate to get us involved
I’m happy because I like what I do
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Inappropriate?Cool, I will have a look around.
I do most development for mobile devices in C# .NET as well :)
Thank you for your time.
I’m happy with 42tags
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Inappropriate?I think CxImage http://www.xdp.it/cximage/ with the CxImageMNG module would suit your needs.
You would need to create your own dll though.
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Inappropriate?PNG and TIFF are very different. PNG is lossless while TIFF with its JPEG compression is lossy.
From some tests I did with Nconvert.exe, it seems that scanned *pictures* will come out much larger with PNG (One of my scans was turned from 74k-Jpeg to 470k-PNG - almost 7 times bigger!).
While most of the scanned *documets* might come out smaller (this requires further investigation). I converted already-jpeg-compressed-scans and got file sizes that were 50% smaller to 100% bigger with PNG. Of course, that encoding the original scanned document directly to PNG without going through JPEG will probably give better results.
Anyway, I'm not sure the answer can be conclusive here... We'd need better statistics to find out if this might actually save disk-space, and how much.
So far, IMHO, it seems that our file-sizes are fair (as long as the DPI and the JPEG compression are kept within reasonable limits...) - 100-150DPI and 70% compression give out results that are quite good.
I’m wishing these format and patent wars would be less of a jungle :)
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Inappropriate?Yup, I agree with the whole format thingy...
The results are much better for me when I lower the DPI and quality indeed.
Btw. My remark was never meant as criticism, just trying to add my 2 cents to the development.
And I think that already-jpeg-compressed scans will be worse in PNG because there is more noise, and PNG works best with crisp/clean images.
I’m glad the devs have a good chat with me, makes me appreciate the product all the more.
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