Exporting format?

[Mr. Quebec]

Hey guys!

I shoot RAW on my camera (CR2 files). I transfer my RAW files on my computer and then edit and export them as TIFF files. Recently I emailed some pictures and I exported my TIFF files to JPEGs. Even though I have used a compression of something like 30%, my TIFF files and JPEGs were alike in a 100% crop.
So here comes the question :
Should I bother exporting my RAW files into TIFF files or directly export them as JPEGs?

My RAW files are 14 bits files. JPEG files have only the option of 8 bits. (TIFF files may have both 8 and 16 bits) So I guess that when I export 14 bits to 8 bits, I lose information, but when I export them into 16 bits TIFF files, I have useless information. Correct reasoning?

Also, although it’s not an issue now, TIFF files are heavy. We’re talking about 100 Mo files! That’s something I don’t understand. RAW (about 25 Mo) to TIFF (around 100 Mo ) to JPEG (not much, around 5 Mo if memory serves me well 🙂 )
If TIFF files and JPEGs have similar picture quality, why TIFF files are so heavy?

[Ezra Morley]

Oh boy, where to start! 🙂

First, I’d be interested to know what software you’re using; Lightroom? Darktable?

Second, I’d be interested to know what the 30% compression you talked about is. I assume it’s JPG compression? When I compress JPG files, I usually use about the 70-99% range. 30% compression is really compressed, I would certainly have thought that you would see a difference at 100% magnification. You might be interested in reading my thread about JPG compression here: https://www.lenspiration.com/forums/topic/resize-and-compression-tools-for-photographers/

So here comes the question :
Should I bother exporting my RAW files into TIFF files or directly export them as JPEGs?

That totally depends on what you plan to do with the exported files. If you’re planning on printing, then TIFF is probably a good idea. If all you’re going do with it is post it online, or view it on your laptop, then JPG is perfectly acceptable. Your hard-drive will thank you… 🙂 Generally, I would say there’s not any point to export to TIFF except for printing. If you’re worried about maximum quality, just remember that you always have your RAW file (which is lossless) and you can always re-export to a TIFF if you need it. Plus, you said yourself that you can’t see any difference between the TIFF and the compressed JPG! 🙂

My RAW files are 14 bits files. JPEG files have only the option of 8 bits. (TIFF files may have both 8 and 16 bits) So I guess that when I export 14 bits to 8 bits, I lose information…

That is absolutely correct. But unless you plan on editing the file further, it doesn’t really matter. Your cheap laptop monitor can only see 8-bits anyway, so visually there shouldn’t be any difference. The main advantage to 14-bit RAW is all the data that it has stored up that you can bring out in editing. Think about pulling out the shadows in Lightroom or Darktable and still being able to see details. That’s the kind of data that your 14-bit RAW has, (which the 8-bit doesn’t).

but when I export them into 16 bits TIFF files, I have useless information. Correct reasoning?

Yes, to some extent. Here’s a good illustration which I borrowed from here: http://www.bobatkins.com/photography/digital/raw.html (A very good read by the way!)

• “If you want to access all 12 bits of the original RAW file, you can convert to a 16-bit TIFF file. Why not a 12-bit TIFF file? Because there’s no such thing! Actually what you do is put the 12 bit data in a 16 bit container. It’s a bit like putting a quart of liquid in a gallon jug, you get to keep all the liquid but you have some free space. Putting the 12 bit data in a 8 bit file is like pouring that quart of liquid into a pint container. It won’t all fit so you have to throw some away.”

[See also: http://www.learn.usa.canon.com/resources/articles/2016/ipf-pro1000/16-bit-workflow.shtml ]

As to the reason that your 14-bit RAW is only 1/4 the file-size of a 16-bit TIFF, here’s a good explanation: (Taken from here: http://photo.stackexchange.com/questions/61483/why-do-modern-dslrs-support-jpeg-but-not-lossless-formats-other-than-raw/61485 [The discussion was about PNG, not TIFF, but some of the same principles apply.])

• “Raw files are actually very space efficient, since they only store one greyscale channel, in 12 or 14 bit per pixel. A lossless 24bit format will inevitably create larger files, while dropping 4 or 6 bits of dynamic range. A 48bit format would even be twice as large, of course.”

The reason that a TIFF is so much “heavier” than a JPG is that the TIFF is completely uncompressed. Here’s an experiment for you to try for yourself: Take a JPG file and open it in GIMP. Look at the bottom of the GIMP window in the toolbar, and you should see something like this:

That picture that I opened in GIMP was a 5.28MB jpg file. Why does GIMP show that it “weighs” 100.6 MB then? Someone has already done a good job of answering that here, so I won’t try to re-explain. I’ll quote the relevant parts here.

– http://photo.stackexchange.com/questions/15184/why-does-photoshop-show-my-jpeg-files-unusually-large –

“TIFF and JPEG files are “containers” for image data. TIFF are often compressed losslessly — like a .zip file — or sometimes, not compressed at all. JPEG files have a similar lossless compression, but also discard data so that there’s less information to store. So you take the full bitmap image and squish it down into a smaller file. The algorithm attempts to discard data that humans won’t notice — kind of like how mp3 audio files discard high frequency noise.

However, when you go to display an image, the data gets reconstructed from the file into a simple bitmap: an array holding 8 bits per color × 3 colors × the image width × the image height. As an aside, it’s possible to have other color depths, but don’t worry about that just here. The point is, regardless of how you’ve stored them, the actual image unpacks to this collection of data, where the space required is simply based on the dimensions, not the content. This uncompressed image is what is displayed, and what you work with in photoshop.

Even though you initially compressed in a way that discards data, once rendered into viewable or editable form, the places for the image data are the same: still the same-sized buckets for storing information, and still the same number of them for the same image resolution. A flat-color solid black uncompressed image takes the same space as a very detailed photograph — even though there’s more information in the detailed one, there’s the same amount of data required for display and editing.

This has a key repercussion, which is that the compression is “lost”. If you used a compression that keeps all the data (like that normally used by TIFF, PNG, or PSD), there’s no real problem: if you save again, it’s different, but still lossless. However, when you save again as JPEG, you go through the process of throwing out information all over again, meaning your image gets worse every time you re-save.”

There, does that answer all your questions? 🙂

P.S. You can also losslessly compress TIFF files to help save on storage space. See here for more info: https://havecamerawilltravel.com/photographer/tiff-image-compression

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[Mr. Quebec]

Thank you so much, @buddingphotographer!

First, I’d be interested to know what software you’re using; Lightroom? Darktable?

Neither of them. 🙂 I use RawTherapee and GIMP.

Second, I’d be interested to know what the 30% compression you talked about is

Yes, it’s JPG compression. And sorry, I wrote it backwards. I maintained a 70% quality (I compressed 30% of the picture, I didn’t bring the JPEG to a 30% compression. You’re right, I should certainly see a difference at a 100% magnification with such a compressed file!)
BTW, I used GIMP to export TIFF to JPEGs. GIMP warned me that it can’t support 16-bits and have to adapt my file to 8-bits. Maybe it has something to do with file size?

If you’re worried about maximum quality, just remember that you always have your RAW file (which is lossless) and you can always re-export to a TIFF if you need it.

You’re right. I didn’t thought of that one! I think that’s what I going to do. I bought a 1 To hard drive, so it’s not a problem right now, but I don’t have any reason to keep large TIFF files. And about JPEG vs. TIFF quality, I just gave a quick glance. I didn’t really go into a ”pixel-peeping” exam.

I think I’ll go with JPEGs. I know that TIFF files are better for maximum image quality, but I have to remind myself that I’m not a pro photographer and most of my pictures won’t go out of my hard drive. If I am ever asked for the highest possible quality picture, I’ll just go to my RAW file and export it as a TIFF file.

• This reply was modified 54 years, 9 months ago by .

[Ezra Morley]

Ah, RAWTherapee! I’m supposed to be making a tutorial on how to use it for basic edits, but I just haven’t gotten a round tuit yet. 🙂

If you do need to export 16-bit TIFFs for any reason, just uncheck the “Uncompressed TIFF” option, and you’ll save a tidy little percentage of MB. Since TIFF compression is lossless, you don’t lose any info that way. It just requires a little more processor power when you open it.

Yep, the official GIMP software doesn’t support 16-bit editing yet. And no, it’s not really anything to do with file size, per se, it’s a matter of bit-depth. However, if you don’t mind trying “incomplete” software, GIMP 2.9 does support it! It’s slow, and might crash pretty easily, but it’s there. You can download it here: http://partha.com/downloads/Gimp-2.9.3-64bit.exe

As for TIFF vs. JPG, a JPG saved at a 100% compression ration should have about 99.9% of the quality of a TIFF at a huge savings in file size! (That’s my own statistic, don’t consider it official 🙂 ) In fact, some of the newer JPG codecs are considered lossless at 100%, but I don’t know of any software that uses that particular implementation/codec.

The only reason I can think of to use a 16-bit TIFF is to preserve maximum editability for other software. Like if you send a picture to a printer to be printed, and they determine that it’s too dark, so they brighten it a bit before printing. A 16-bit TIFF will do much better than your 8-bit JPG in that situation.

Thank you for asking that question! I learned a lot myself when researching this question, so it was good for me too!

[Mr. Quebec]

Thank you again so much, @buddingphotographer 🙂
Glad I wasn’t the only one who learned something!

I’ll have to try to compress my TIFF to see if it is worth it. Good to know that it’s lossless!

As for TIFF vs. JPG, a JPG saved at a 100% compression ration should have about 99.9% of the quality of a TIFF at a huge savings in file size!

And if I compress my JPG more drastically, say 80 or 90%, will the ratio JPEG vs TIFF quality drop by a great deal, or is it negligible?
Anyway, I can’t remember, but I don’t think that compressing a lot a JPG makes a huge difference in file size…

[Ezra Morley]

And if I compress my JPG more drastically, say 80 or 90%, will the ratio JPEG vs TIFF quality drop by a great deal, or is it negligible?
Anyway, I can’t remember, but I don’t think that compressing a lot a JPG makes a huge difference in file size…

I can’t really tell you that; my idea of “quality” may be different from yours. 🙂 All you have to do is save a few JPGs at different compression ratios, and compare to a TIFF! FastStone Image Viewer has a compare feature that makes it very easy.

Depending on the software you use, compressing even a little bit can have a huge impact on file-size! Here’s an example from Lightroom. (Taken from this thread: https://www.lenspiration.com/forums/topic/resize-and-compression-tools-for-photographers/) As you can see, when you go from 100% quality to 90% quality, you lose 1/3 of your “weight”; from 92KB to only 33KB!

I don’t know what Adobe did, but their JPG engine for Lightroom is very good, if I remember correctly, there wasn’t any visible difference between 100% and 75-80%! And the file-size difference is at least 1/2, if not less!

I never save JPG files at 100% any more, unless for special purposes. The whole point in JPG is to save on file-size, so if you’re going to use it, make it save! If you need lossless, use TIFF or PNG.

[Matthew Stevens]

Basically, if I am going to edit a photo further outside of Lightroom, I will export a tiff. Otherwise, it goes out as jpeg. Like, say I needed to do some touchup work with the healing brush or whatever in Photoshop, I’ll save a tiff out of Lightroom and then work on it in Photoshop. The ONLY reason for this is that tiffs are lossless…even if they are compressed, information does not get discarded from the image when you save your edits.

On the other hand, a jpeg is LOSSY. Every time you save, the jpeg engine in the software you are using analyzes the image according to how the human eye perceives color, contrast, etc., and then discards some information from the file in order to save space. If you edit, then save a jpeg a whole bunch of times, each time it’s discarding information, and each time you save, your image quality goes down.

That said, if you are finished making edits to the file, either in LR or PS, just export as a jpeg. It will look the same to your eye, and the file with be orders of magnitude smaller (as you figured out…)

So, my standard workflow is either:
lightroom -> jpeg (if I’m not making edits outside of lightroom), or
lightroom -> tiff -> jpeg (if I am making outside edits in gimp or PS)

You pretty much covered all that already @buddingphotographer…Just wanted to add my 2 cents.

[Ezra Morley]

@MrStevens,

Thanks for commenting! I guess that is one area where a TIFF comes in handy (for further work in PS). I don’t have Photoshop, so I didn’t think of that possibility. 🙂 As I said earlier, GIMP doesn’t yet support 16-bit, so I don’t see any real benefit to saving an 8-bit TIFF instead of an 8-bit JPG. But for someone who does have both Photoshop and Lightroom, and wants the best possible quality, that’s definitely the way to go.

[Matthew Stevens]

Well, the same thing applies to GIMP. I do a lot with gimp, there’s some stuff it does better that PS. You still wind up losing image quality on every save because of how jpeg compression works, so just work with tif until you’re finished making your edits, then export as jpeg. That way you get max quality + small files. 16 vs. 8 bit has less to do with it than does lossy jpeg compression.

[Ezra Morley]

True, I guess I haven’t worried about compression too much; I’ve never seen a file any worse for the wear just from being saved once or twice. Actually, to tell the truth, I very rarely go from Lightroom to GIMP and back (if ever). I mainly use GIMP for design projects, or for helping people with their picture problems, in which case I’m usually working with JPGs anyway! 🙂

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