png vs tif

[qiang_lin]

Hello,

 

I understand that png was designed to replace gif to avoid patent issues, thus

it was not optimized for photos. Since it is lossless format, I gave it a try

days ago. Compare to the same images saved as tif with or without compression,

the png files were smaller.

 

My question is, if png has smaller file size, preserve the same information as

tif (at least the image itself), and is widely support on many platforms compare

to jpeg2000, why most people use tif as the standard lossless format (e.g. photo

finish, etc.)?

[steven_clark]

Support for advanced PNG features like high bit-depth and color profile information is implemented less frequently than the same features in TIFF. That, and there may not be enough of a difference between the two to warrant change.

[KenPapai]

TIF doesn't compress, PNG does. TIF is almost like a pure BMP. It's easy to compress the size of a file and not lose any info (one example, ZIP files).

 

Do not confuse lossless compression with lossy Compression. JPG is Lossy (but if saved as level 12 in Photoshop it takes years to notice degradation of an image file ;).

 

If your image is of a pure blue sky and was shot with a 12MP camera, you could theoretically compress that to a tiny 128KB file with zero loss of image data.

[andrew_duncan]

Actually, the <a href="http://partners.adobe.com/asn/developer/PDFS/TN/TIFF6.pdf">TIFF specification</a> includes a number of compression schemes. While a TIFF file can be uncompressed (like a Windows DIB/BMP) it doesn't have to be uncompressed. The compression schemes usefull for 8 or 16 bit photographic images are LZW, JPEG and ZIP (these are the options available in Photoshop and PS Elements). However, I have never found a reason to use JPEG compression in a TIFF file, you are better off creating a JPEG file.

 

<p>ZIP compression is the same compression scheme as used in PNG. It is an extension to TIFF (and is not in the specification). As such it is not supported by as many programs as LZW or JPEG.

[qiang_lin]

Thank you for your responses. Actually I'm pretty familiar with compression algorithms as a communication/signal processing engineer. My question was: with similar or smaller file size and support on many platforms, how come png is not as popular as tif?

 

I guess it is because png is relatively new compare to tif, thus not well supported by photo finishing equipments. I read that there are some annoying bugs in implementations of web browsers despite the fact png was designed for web applications in the beginning.

 

Thank you all for your time and input.

[jeffmather]

PNG never took off for several reasons. JPEG produced smaller files for continuous tone imagery. GIF and TIFF had entrenched market dominance in terms of image file creation and browsing software. PNG didn't have any advantages at storing metadata or imagery over TIFF for most users.

 

But primarily, there really weren't that many people who felt obliged to use GIF. UNISYS was only going after the big money when it came to patent enforcement, and all of the readers (browsers, editors, operating systems) had already licensed GIF. Almost everyone creating GIFs had Photoshop or another application that licensed the patent, too. So there was no real reason to change.

 

Plus, GIF supported simple animation at a time when the web wanted it. And JPEG-2000 wasn't around at the time.

[geoff_foale]

I save my better images as TIFF, just to be certain. Those that aren't so good but I don't want to ditch go as PNG to save space.

[emre]

GIF's LZW patent expired in 2003, but it does not matter since the file format is dead.

 

PNGs take longer to read and write than TIFFs.

[rogerjporter]

I have just started using an online printing service that only prints from jpegs or png formats.

traditionally, when i need big prints i have used tiffs (16 inch prints and up). my first photo

up is a 28 mb tiff, which compressed to a 10 mb png. will i see a huge difference on a

16x20 between these 2 formats? i had never even heard of a png until today. thanks!

[qiang_lin]

Roger,

Since both tif and png are lossless formats, the image itself should be the same. However, the extra information such as gamma, etc. might have different implementation in different systems. Therefore, I don't think you will see difference in terms of sharpness. Give it a try, if you don't see difference in color, it should be fine.

[jeffmather]

Not to be anti-PNG -- I think it's a good format -- but as someone who has implemented

both formats, I don't think it has anything to recommend it over TIFF or PSD for anything

except saving for the web. (Or when you have to use it, as one of the contributors indicated.)

While PNG does have gamma, TIFF and PSD can contain ICC profiles, which are much better.

TIFF and PSD have support for both LZW and deflate compression. And TIFF has much richer

metadata support.

[bill_tuthill]

How can anyone say PNG is a dead format when every stock graph

on finance.yahoo.com is a PNG image?

[jeffmather]

It's definitely not dead; it's just not the best format for photographs. Graphics yes;

photographs no.