Converting from TIFF to PNG??

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daryl wrote on 9/16/2010, 11:16 AM
OK, here are my 2 cents.
PNG came along because GIF was about to cause ownership problems, the format is owned by a private company. I have not heard any more about that in years.

I use TIFF ONLY for print images, would not even consider putting them on the timeline of Vegas.

The examples in the previous post were pretty high res, so of course they would all look good on a browser, 4288X2848 240 ppi. Start with a 720X480 (or smaller) at 72 ppi, compress it a time or two with jpeg and you'll start to see some artifacts, especially if you pan/zoom in on it. PNG would be much cleaner.

Anyway, my personal preference is psd for anything that I may zoom in on, beyond that, I don't care if it's jpg or png if the image is clean, none of these formats causes any problem with Vegas on my system.
John_Cline wrote on 9/16/2010, 12:38 PM
While PNG does have an 8-bit mode like GIF, it is usually used in a 24-bit format and unlike JPG, it can contain an alpha channel. Also unlike JPG, 24-bit PNG is absolutely lossless.

Also, in video applications, DPI is totally and completely meaningless.
Jøran Toresen wrote on 9/16/2010, 1:47 PM
After reading this thread, I want to convert all my photos (JPEG) to PNG. Questions:

1) Does all application produce the same quality when I convert from JPEG to PNG?

2) Or does the quality depend on which application I use? If so, which program should I use to convert my photos?

3) So far I have been looking at the converters in XnView and FastStone Image Viewer. Should I deselect “Interlaced” for my photos? Which compression level should I choose? None, 1…8, Max? Are there other important settings?

Jøran
OGUL wrote on 9/16/2010, 2:42 PM
www.sierradescents.com/jpeg8.jpg 1.39 MB
www.sierradescents.com/jpeg10.jpg 2.65 MB
www.sierradescents.com/jpeg12.jpg 6.73 MB

Excellent pics.
Why their file sizes differ so enormously??
Chienworks wrote on 9/16/2010, 2:47 PM
Ideally they should all produce exactly the same result. There is a slight possibility that some applications might use an inferior JPEG decoder, but such an application is probably so poorly written that it doesn't function well enough to have become popular. There is no difference between any PNG encoders that can successfully make a PNG file. They all use the same algorithm and that algorithm is lossless.

There are no compression levels in PNG. The algorithm supports 8 bit or 24 bit, though almost all encoders don't offer a choice and will only encode 24 bit. Most applications offer no options other than file name and perhaps inclusion of alpha channel.
Chienworks wrote on 9/16/2010, 2:49 PM
JPEG file size varies with the compression level. More compression creates a smaller file with more loss and artifacts.
Jøran Toresen wrote on 9/16/2010, 2:56 PM
Thank you Kelly. But when I use FastStone Image Viewer (or XnView), I can choose the Compression level: None, 1…8, Max.

Jøran
rmack350 wrote on 9/16/2010, 4:50 PM
PNG does indeed support a compression level but this is more like zip file compression. All the levels are lossless but some are much slower to inflate/deflate than others.

The discussion of PNG Vs JPG misses some points. JPG is often "good enough" when talking about photographic images. PNG, is better on principle because it's lossless. Not only is it lossless but it supports an 8-bit alpha channel, meaning you could cook a semitransparent drop shadow into the image. That's very cool. PNG is especially good for graphic elements where you might need solid colors, crisp edges, and areas of transparency.

We talk a lot about compression and about how a JPG image is smaller than a PNG. Sometimes we mistakenly assume that the small jpeg images should consume less RAM than PNG when they're used on the timeline. This is probably not quite true since what we should be concerned with is the image's memory size while decompressed. In a decompressed state a 654x480x24bit jpg file should consume as much RAM as a 654x480x24bit PNG file. Just sayin'.

Rob

Terje wrote on 9/17/2010, 11:57 PM
[i]Andy_LTerje, I find your lack of faith in JPEG disturbing...[/b]

I do not have a lack of faith in JPEG. JPEG is a good format for image delivery if your delivery medium is digital online download. It is a terrible format for image archival.

This is exactly analoge to print images vs negatives. You don't throw away your negatives just because you have printed them as a standard size photo. Archiving as JPEG is fine for snaps of the kids birthday party, but for your priced photos it is absurd.