TIFF Compression Algorithms

[chief]

I'm curious. When saving images as TIFF files, what compression formats are you folks using? What are the pros and cons of various options?

Thanks.

[Steve Foss]

I never compress a TIFF image file when I'm doing the printing. The point of using TIFF files is that there is no compression, and thus no loss of image quality. Any compression of a TIFF file, regardless of whether you save as a jpeg in photoshop or drop zip it after saving in photoshop, will degrade IQ.

I prefer to send images burned as TIFFs on CD, which delivers the best quality available. If I need to transmit a compressed file electronically, like for posting online or easier transmission to an FTP site or via e-mail to a publication client, I save it as a jpeg, which is universally readable. And then the compression factor varies based on what the client wants. I generally use as little compression as possible because the more compression the poorer the quality when it's opened.

For transmitting electronic files to my print lab, which specifies jpeg, I save them at the highest quality setting, 12, which offers the least compression. For newspaper clients, whose demands are less stern, I may go down to about an 8.

The lowest-compression jpeg (setting 12) will still be smaller than the original TIFF file and will open on the other end into a higher quality image than if you took a TIFF, zipped it and sent it to be unzipped at the other end. If the image is too large to send as a low-compression jpeg, I burn it to CD as a TIFF and snail mail it.

I'm not really sure if that answers your question.

[Dbl]

TIF LZW stores it with recoverable full quality in a lossless format. LZW, Lempel-Ziv-Welch is named as such after its developer. If you do a search you will find some more information in it. I believe there are a couple of other loss-less formats but the above is the most popular.

If I store a TIFF I generally just store it full size, I don't work in that format that often. With hard drives being as cheap as they are these days I would not be to concerned about compressing for storage. Backup with a hard drive or DVD stores a lot of pictures.

Is that what you were looking for?

[Steve Foss]

Dan, I don't know if that's what chief had in mind, but it's good info for me to know. I doubt I have much need for LZW, but I learned something new today, so thanks for that.

[chief]

Gentlemen,

Thanks for the replies. All info is helpful, and it's especially useful to hear the rationales of other photogs.

Specifically, I was playing around in PS Elelments 5.0, experimenting with saved files in a variety of formats. When saving in TIFF, an available option screen lists the following compression formats: none, lzw, zip, and jpeg. What I understand now, thanks to you guys, is these options exist primarily for transmission. If I want to save a TIFF file to CD/DVD I would choose "none" as my compression option. After all, I want to save a full size image--without compression. My motivation for all this is to save images in the least "lossy", most archival, format.

Thanks.

[Steve Foss]

Chief, sounds like you've got it figured out. TIFF with no compression format is the way all the pros I know save their working image files. I shoot RAW, and the first thing I do after I open the image in CS2 and before I start working on it is save it as a TIFF so the native, original file remains untouched.

[Paul]

Here is my Tiff question. Why is it than when I convert from Raw to Tif if doesn't save any photo info such as fstop, iso, ect. Or am I doing it wrong?

[Steve Foss]

Paul, I don't know which RAW converter you're using, or whether some converters strip exif data.

I just use Photoshop CS2, which already has the RAW plug-ins for my camera bodies, and when I open a RAW image and save as a TIFF, the exif comes along.

[IFallsRon]

There was a time that Imagesetters for magazine film production had trouble with compression, especially LZW, so we never used it. In general, there is no need to use a compression filter as the TIFF is already a more compact package.

[Dbl]

Quote:

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There was a time that Imagesetters for magazine film production had trouble with compression, especially LZW, so we never used it. In general, there is no need to use a compression filter as the TIFF is already a more compact package.

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Actually Ron that is incorrect. We are talking RAW and TIFF. RAW is in almost all cases a compressed format already, TIFF is not. RAW files are 12 bit files while TIFF can be saved as either an 8 bit or 16 bit file. If you look for example a 6mb camera produces around a 6mb RAW file, if saved as an 8 bit TIFF it would be 16mb and if saved as a 16 bit file it would be 32mb in size. If you saved as JPEG it would be around 2-3mb in size.

It really has to do with color, a 12 bit RAW file contains 4096 pixels of shading or values, however you want to describe it. An 8 bit file only contains 256 values and a 16-bit image provides us with 65,536 values. What that allows us to do is do considerably more manipulation to the image over a wider tonal range.

Why don't we just do everything in 16 bit? You do if you want the most from each image, but remember the file sizes you will be working with. Remember also that printer drivers are 8 bit so matter what you do you will lose some of those values when you go to print output.

This is a basic explanation, believe me there is considerably more to this than I am describing. There are a number of good sites and books that can help you along this road if you want to go down that path. If you are working for example as Steve does with print out put it matters, my needs are for high volume small print size so 8 bit JPEG works for my color renditions. Landscape and wildlife photographers would work in a larger bit size, journalist and sports photographers can use a smaller bit size. Whatever your requirements are you have a choice in using the appropriate size. This more completely answers Chief's question about TIFF and compression, I just didn't know how deep we were going with this, but other discussions led us down this road, sorry.

[Paul]

Quote:

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Paul, I don't know which RAW converter you're using, or whether some converters strip exif data.

I just use Photoshop CS2, which already has the RAW plug-ins for my camera bodies, and when I open a RAW image and save as a TIFF, the exif comes along.

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I had been using the canon software. I will try using PS withthem. I am heading out to the PGI convention tonight so I will have a few hundred fireworks shots to play with. I will post some results.