PNG for Photo

<p>Is PNG format suitable for photos? I like PNG b/c it is lossless. However, when I research on this, people seems to be saying that PNG is best for graphic arts files rather than photos but it is not clear to me. I don't mind that PNG results in larger file size than JPG as long as the image quality is good. Your thoughts.</p>

<p>To quote Wikipedia:</p>

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<p>Using PNG instead of a high-quality JPEG for [photographic] images would result in a large increase in filesize with negligible gain in quality.</p>

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<p>The image quality of a photo in PNG is "good," but so is a much, much, much smaller JPEG file. Support is also still considerably broader for JPEG. <br /> <br /> If you're preparing for the web, use JPEG and make everyone happy. If you're preparing for print at a typical lab, use JPEG and make everyone happy. If you're just tossing these on your own hard drive, do whatever makes you happy, but don't expect a tangible benefit (because, unless you're setting your JPEG quality far too low, there isn't one).</p>

PNG is not always lossless; it just supports lossless compression (as well as lossy compression). TIFF is a good lossless file format for photographic images. It used to be my understanding that PNG doesn't support colour profiles, but I may have been mistaken on that one.

<p>Colin O,<br>

When I save PNG with Photoshop, it never offers the options of compression levels or compression method. Other programs I use offers choices of compression level but not method. How do you choose lossy compression for PNG (not that I will but am just curious.)</p>

Sorry, that's a misunderstanding on my part - I don't use PNG. After a brief look at the Wikipedia article on PNG, it seems that it does in fact always use lossless compression - a compression algorithm called 'DEFLATE'.

<p>A PNG is kinda like a TIFF that is always compressed with ZIP compression and has some variation to the compression patterns that can let it work better with solid-color images. PNGs works well for graphics and in some cases may be smaller than a decent JPEG if there are solid tones. The problem is it's used so much for online graphics that support for features like embedded profiles or high bit-depth can be hit-or-miss to non existent.</p>

<p>PNG is a newer format than some. For print purposes it is generally better to use a TIFF, compressed or not. If you have the space to store a PNG you probably have twice that much space to store an uncompressed TIFF everyone can read.</p>

<p>Is lossless PNG inherently better in picture qulaity than JPG of the same file b/c the former is lossless?</p>

<p>Steven,<br>

You are right. After thinking about it more, I don't really see a real benefit of PNG for what I do. I save most everything in PSD for myself. For clients I have always been giving out JPEG. I was thinking that PNG maybe a better "bridge" option between the two. Now, I am thinking to give out LZW compressed TIFF instead of JPEG. So the new question is this:<br>

I know uncompressed TIFF is universally supported (except for web). How about LZW compressed TIFF?</p>

<p>Hi,<br>

Most modern browsers will as far as I know handle PNG, so you can use PNG on the Internet. As I see it, the main advantage of JPG is the small file size due to lossy compression and the main advantages of PNG is that it is lossless and it handles something JPG does not have at all: transparency (partial transparency or <em>alpha transparency</em>). The latter may be important for graphical designs which may very well include photographs.<br>

There is something called TinyPNG that is, as I understand it, a lossy compression method that will reduce the file size of PNGs. It do so by reducing the colors in the original and using the indexed color mode.<br>

Is PNG better than JPG for photographs? There is no yes or no to this question since it depends on your requirements/usage. There might be one very important factor other than file size and lossless compression to consider for photographs though, and that is whether sites like photo.net do allow for other formats than JPG.<br /><br /></p>

 

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<p>people seems to be saying that PNG is best for graphic arts files rather than photos</p>

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<p>I believe this is because they presupposes that file size is the main factor. For use on the Internet that may very well be a correct assumption since graphics tend to have very few colors compared to a photo. Few colors together with indexed mode will give small files for PNGs.<br>

But on the other hand, as you say: File size may not be that important. And lossy compression may not be desirable in some situations.<br>

Personally I use 99.999% JPG for the Internet (and the other 0.001% might very well not exist), just because it has become a habit and because it is very easy in Photoshop to just Ctrl-Alt-Shft-S an image when I want to save it for Internet usage (it takes care of everything without me needing to do thinking stuff).</p>

<p>Cheers,<br>

Frode Langset</p>

<p>(And excuse my English. It is not my native language)</p>

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<p>I know uncompressed TIFF is universally supported (except for web). How about LZW compressed TIFF?</p>

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<p>LZW has been her for years (older than zip as far as I know), so if some software can handle TIFF I would expect it to handle LZW compression as well, at least uncompressing. LZW is also a very simple algorithm to implement. Conclusion must be that the question is not about compression, but if your clients have software that handles TIFF or not.<br>

I do not have much experience with TIFF, but I have seen the advice not to use LZW on 16 bit TIFFs, only on 8 bit TIFFs as LZW may more often than not result in larger files when compressed with LZW. ZIP is better for 16 bits.</p>

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<p>It used to be my understanding that PNG doesn't support colour profiles, but I may have been mistaken on that one.</p>

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<p>When I make a screenshot on my Mac my custom monitor profile is embedded which is one of the reasons I post screenshots of photo edit examples in Adobe apps for forum discussion demos. The file is bigger than if I'ld resaved to jpeg in CS5's Save For Web but not by much. Most forums I post in support up to 1MB uploads which my Mac's PNG format is well within depending on the size of the screenshot in pixels.</p>

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<p>Is lossless PNG inherently better in picture qulaity than JPG of the same file b/c the former is lossless?</p>

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<p>Drag & drop to a layer in Photoshop set to Difference blend mode of a PNG onto a jpeg of the same image or vise versa to see.</p>