TIFF Conversion Question?

[Ron Kruger]

With the PSE 7.0 program I'm testing, and plan to buy, I can convert original low-compression JPEGs to TIFFs. I did this once from a JPEG that I had cropped and processed, and it expanded the file from 3.6 MB to 16 MB.
Yesterday I got responses from three magazine queries requesting CDs of some upland shots. I copied the folder with all my processed JPEGs, but for shots I thought had cover possibilities, I downloaded the original low-compression JPEGs from my camera and converted them (without doing anything else to the files) to TIFFs. These originals were about 10 MB each, and the TIFFs were all 40.5 MB.
Original RAW files I have converted to 16-bit TIFF files come out with around 80 MB.
Does anyone know what's going on here?
Does this mean that TIFFs converted from low-compression JPEGs have about half the information as TIFFs coverted from RAW files? Or does it mean that low-compression JPEGs are automatically being coverted to 8-bit TIFF files (it didn't give me a choice, or tell me how many bits, or maybe I just didn't find the choices)?

[SmartWombat]

It means ... you can't make a silk purse out of a sow's ear.

A low compression (highest quality) JPEG converted to a TIFF contains no more useful information, the image quality and content should be just the same.

Does this mean that TIFFs converted from low-compression JPEGs have about half the information as TIFFs coverted from RAW files? Or does it mean that low-compression JPEGs are automatically being coverted to 8-bit TIFF files

Probably the latter. Possibly both.
Since TIFF uses a lossless compression then doubling the data from 8 bit to 16 bit should approximately double the file size.

[another view]

Going from jpeg to tiff won't do anything other than use more disk space. The benefit mentioned in the other thread is that if you work on your image and re-save several times, there will be no additional compression applied each time you re-save it. If you re-saved a jpeg a bunch of times eventually you'd start seeing problems with the final image.

Jpeg files are 8-bit by definition, but tiff and raw are 16-bit (note that although the tiff format will allow that extra bit-depth information, it isn't present when created from a jpeg). However, most cameras shoot in 12-bit (did I hear some are now more like 14-bit?). Still 8-bit to 16-bit isn't double the amount of information; it's exponential. Tiff converted from raw will remain at 12-bit (or 14-bit) because you're not forcing it into an 8-bit format. Huge file size difference right there.

As I understand jpeg, what happens is that it drops out redundant information and that's why the file size is so much smaller. Shoot something with a lot of detail covering the entire shot - the more the better and as much tonality and different colors as possible. Now take a shot of a clear blue sky, sand or snow that fills the entire frame with the same camera settings. With un-compressed raw or tiff, you should have virtually the same file size. With a compressed file like jpeg or compressed raw (Nikon does it, not sure of others) you'll have a significant difference between these two shots.

[Ron Kruger]

Okay. I've read your posts twice and think I understand (may need to read it once more). Thanks, but bear with me, I want to make sure I understand all this completely and don't mind if I look simple in the process.
So, does that mean that a TIFF file converted from an original, untouched low-compression JPEG has the same information as a RAW file converted to an 8-bit TIFF?

[Ron Kruger]

View said: "Going from jpeg to tiff won't do anything other than use more disk space."
In that case, when I'm sending images via CD would I be better off simply downloading the original, untouched low-compression JPEGs from my camera and copying them to CD, instead of going through the trouble of converting them to TIFFs first?

[OldClicker]

Okay. I've read your posts twice and think I understand (may need to read it once more). Thanks, but bear with me, I want to make sure I understand all this completely and don't mind if I look simple in the process.
So, does that mean that a TIFF file converted from an original, untouched low-compression JPEG has the same information as a RAW file converted to an 8-bit TIFF?

No. A jpg not only has less information because it is only 8-bit, but also because of the compression techniques it uses to make the file smaller and the interpolations (guesses) it uses when it opens that compressed file. And every time that file is saved (as a new file, not just the same file copied) jpg compresses and guesses again. – TF

[OldClicker]

View said: "Going from jpeg to tiff won't do anything other than use more disk space."
In that case, when I'm sending images via CD would I be better off simply downloading the original, untouched low-compression JPEGs from my camera and copying them to CD, instead of going through the trouble of converting them to TIFFs first?

As long as they are never open and saved again, that is correct. The damage has already been done. - TF

[SmartWombat]

does that mean that a TIFF file converted from an original, untouched low-compression JPEG has the same information as a RAW file converted to an 8-bit TIFF?

No.
Shooting the same scene as a JPEG and TIFF the camera will store less information in the JPEG. The files are compressed by leaving out information that is less important to the eye/brain perception of the scene.
A RAW file, even when converted to an 8 bit TIFF, I think likely to have more information.

It would be an interesting test, to see if you could tell the difference - on screen or in print.

[mjs1973]

This may be a little off the topic for this thread, but I think it's something to consider when you choose what file format you are going to shoot in. When you shoot in RAW, you get ALL of the information the camera sees. When you shot in jpeg, or tiff, the camera is making some choices for you that will determine how that image looks when you open it on your computer. A RAW file will let you make all of the choices as to how that image will look.

[Ron Kruger]

Thanks, MJS. I've already come to the conclusion that I will shoot everything in RAW/JPEG to have all my options covered. I understand the advantages of RAW and the ease and universal acceptance of JPEG. And I really appreciate everyone’s patience in answering my questions. It’s all been very helpful. I have another question about “thumbs,” but I’ll start another thread about it, since this one is getting long.
For the vast majority of what I do, JPEG is fine (and preferred by my markets), and I can process it in files small enough to fit the parameters of email. One thing we haven’t addressed is resolution, or dpi, which is a critical component to a JPEG’s image quality.
But since getting this equipment, I have decided to actively pursue cover sales (something I haven’t done for years), and to expand my markets into catalogs and promotional publications. For that, I may attach a JPEG to a query, but submission will be done by CD, where it just makes sense to put all the file information and image quality possible.
However, I do believe JPEG is getting a bad rap here, at least low-compression JPEGs. Since going digital in June of ‘08, I’ve sold and had published three covers, without any request for original or TIFF files, and I’ve been pleased with the 8X10 cover reproductions.
And there must be something more to a TIFF file converted from a JPEG than "just a larger file," otherwise the design/photo editor I know (with over 20 years at the job) wouldn't do it as a regular practice.

[Ron Kruger]

I noticed something yesterday. I converted some RAW files to 8-bit TIFFs, and the file came out exactly the same size (40.5 MB) as the files I converted from JPEG to TIFF.
Looks suspiciously like the same thing from two different directions.
What do you think?

[freygr]

With the PSE 7.0 program I'm testing, and plan to buy, I can convert original low-compression JPEGs to TIFFs. I did this once from a JPEG that I had cropped and processed, and it expanded the file from 3.6 MB to 16 MB.
Yesterday I got responses from three magazine queries requesting CDs of some upland shots. I copied the folder with all my processed JPEGs, but for shots I thought had cover possibilities, I downloaded the original low-compression JPEGs from my camera and converted them (without doing anything else to the files) to TIFFs. These originals were about 10 MB each, and the TIFFs were all 40.5 MB.
Original RAW files I have converted to 16-bit TIFF files come out with around 80 MB.
Does anyone know what's going on here?
Does this mean that TIFFs converted from low-compression JPEGs have about half the information as TIFFs coverted from RAW files? Or does it mean that low-compression JPEGs are automatically being coverted to 8-bit TIFF files (it didn't give me a choice, or tell me how many bits, or maybe I just didn't find the choices)?

Converting RAW to TIFF will give you a 16 bit file with a 12 or 14 bit color depth for a file of around 80 MB before lossless compression (note some programs do not like TIFF compression). But going from JPG to TIFF as JPG is only 8 bit color depth you will only get a 8 bit color file there for it will be only have the size of the RAW to TIFF file as you only have half the color information.