How bad is jpeg, really?

Posted: Sat Mar 18, 2006 6:57 pm

Reasons of economy and convienience led me to the place I currently use to develop my film and scan the negatives to a CD. They seem to do fine, and the resolution is high enough for the print dimensions I want.

However, they only offer jpeg.

I've been reading about loss of quality with resaves in jpeg, but how much image quality am I really losing if I can manage to get all my editing done in a single session and save once?

Posted: Sat Mar 18, 2006 7:08 pm

Well, there's no rule that you have to save in jpeg. You could save in tiff, if you do see any meaningful degradation from one edit/save to the next.

:) keithwms

Posted: Sat Mar 18, 2006 7:29 pm

Well, yeah, but I guess I'm asking a really basic, general question. I'm a novice, and there are so many variables I'm feeling a little frustrated. I couldn't tell a jpeg artifact from my own over-sharpening at this point, so I guess I'm just trying to figure out whether the jpeg thing is worth worrying about. How many saves is too many? I guess the file is saved when the negatives are scanned to CD, then I save it after editing, and it is saved again when it is uploaded to an on-line printing service. Are all these saves ones that result in loss? Are three saves enough to make a difference?

Thanks.

Posted: Sat Mar 18, 2006 7:44 pm

Don't be frustrated, all of us went through this and many of us are still going through it!

In my experience, unless you really know how to see the jpeg degradation, you won't see it until after many edit and saves. Now, if you are going to print a richly detailed image at 11x14" or larger, then that's a different story... you'll usually want to keep every ounce of detail through each edit.

Why not take a little time and create a parallel workflow until you have convinced yourself that a few jpegs saves aren't costing you too much detail. How much degradation is too much is a very individual thing- some people will say that saving in jpeg is the end of the world; others will say that tiff files are oversized for their merits.

So in the end I think you have to try both methods (jpeg and tiff workflow ) and decide for yourself. I do think that archiving in tiff is wise, if you can afford the disk space.

:) keithwms

edit:spelling

Posted: Sat Mar 18, 2006 7:59 pm

Thanks Keith. I suppose like many others, I'm squeezing in my photography hobby among all my responsibilities. The place that offers only jpegs is five minutes from my home, with one hour turn around, and I can submit files via internet to print with the same turn around time. Working with this place, I can go from camera to print in a few hours. Having feedback that quick in the learning curve helps, especially when all I have is a few hours to devote to the hobby. But it doesn't mean much if I'm handicapped by the file format.

It sounds like, for my purposes, the file format isn't an issue.

Thanks. Now I can turn my attention to the things that are an issue.

Posted: Sat Mar 18, 2006 10:52 pm

It wouldn't be bad to get in the habit of converting the jpeg scans to tiff, then editing in tiff, and saving yourself a copy in tiff before converting back to jpeg. I often use White House Cutom Colour for my prints, and they only print from jpegs (even though I start in RAW), but all my prints from them (up to 16x20) have been great.

Posted: Sat Mar 18, 2006 11:14 pm

I appreciate the input. After pondering this some more, I realized that, no matter what, I still have the negatives. If I end up with a shot that deserves special attention, I can always take the negative in to be scanned again.

Regarding saving tiffs, is this better than saving in the native format of the software? Oh, wait. I think I just answered my own question. The issue is long term storage, and what formats are most likely to be around in 20 years?

Posted: Sat Mar 18, 2006 11:51 pm

Jpeg is no real problem if you are an average amateur photographer and don't want to get large prints made, my camera will shoot in Tiff or jpg, I chose to use jpg due to hard drive size constraints - Jpg is 1.5 Mb compared to Tiff 9.2 Mb - Jpeg's print OK at 4"x 6".

If I am doing a simple edit - resize, curves etc in one hit, I just do it in jpg and re-save you can't really notice the difference.

If I am doing major editing, changing backgrounds and that sort of thing I convert to tiff to work on it and save the result as jpg, or if I have to do noise reduction, I use Picture Cooler, and if I process it as a jpg it saves what was a 1.5Mb jpg as a 700Kb jpg and strips the Exif data - if I process it as a Tiff, the saved file is the same size and the Exif data is preserved.

I hope this is of some help to you, I don't think getting hung up on the jpg degradation thing is productive unless you are pretty proficient at your craft, and at this time I don't consider I am.

Max

Premium Member Joined: 29 Oct 2004 Posts: 5758

Saving as a highest quality JPEG is pretty forgiving. You can go through a couple edits and re-saves without noticible loss if you keep the JPEG at 12/12 quality.

I'm not sure what JPEG has to do with print size, as has been discussed, aside from the degradation with lower quality JPEGs that will happen regardless of print size. How is a 12 megapixel 300 dpi jpeg any different than a 12 megapixel 300 dpi tiff? When I order large prints I always do so as a JPEG, just because I can't be bothered to upload a 40 megabyte TIFF file.

Posted: Sun Mar 19, 2006 12:28 pm

drpablo74 wrote:

I'm not sure what JPEG has to do with print size, as has been discussed, aside from the degradation with lower quality JPEGs that will happen regardless of print size. How is a 12 megapixel 300 dpi jpeg any different than a 12 megapixel 300 dpi tiff? When I order large prints I always do so as a JPEG, just because I can't be bothered to upload a 40 megabyte TIFF file.

Well, the point I was trying to make is that if you are going to do a big enlargement, then it's best to keep the workflow as lossless as possible through each edit/save.

Now, if a print service is going to do some resizing or other manipulation for you, then tiff is safer.... but it is much bigger of course!

:) keithwms

Premium Member Joined: 29 Oct 2004 Posts: 5758

I was referring to Max' post (above mine), but I do hear what you're saying.

Posted: Sun Mar 19, 2006 2:39 pm

In my experience a couple of saves in high quality JPEG wont make much difference.

To be safe though I always stay in TIFF until I am finished with my editing and then convert to JPEG as the last action.

One purpose for which I strongly advise against JPEG is archiving. This has nothing to do with quality, and everything to do with survivablility.

JPEG and indeed all compression systems work by removing redundant data from the file. For example a simple text compression system to make this forum's database smaller might replace the words "nice shot" with a "1" and just store "nice shot" once in a table with other frequently used phraises.

The problem with this is that if the compressed database becomes corrupt such that the lookup table is damaged, then every time someone on the forum has said "nice shot" will be turned into gobbledegook.

Over time all data storage media decay. CDs, Flash cards, Hard drives, tape backups everything. Eventually some of the vital data bits which make up your beloved photos WILL become corrupt. Stored in uncompressed TIFF its likely that the files will still open and show only minor defects, but stored as JPEG they may have drastic problems or even not open at all

Posted: Sun Mar 19, 2006 10:09 pm

drpablo74 wrote:

I was referring to Max' post (above mine), but I do hear what you're saying.

My point was that for 4"x 6" prints Jpeg's worked well, I made no comment about any other size! I have a 3.2 Mp camera, the few photos I do get printed are 4" X 6". I have no knowledge of how they would perform at larger print sizes as I have never had any printed, as for 12 Mp Jpeg's I made no mention. My reference to Tiff was that I did not SAVE in that format because of storage space constraints.

Max

Premium Member Joined: 29 Oct 2004 Posts: 5758

Gotcha.

Yeah, JPEG is fine for all print sizes. TIFF is worthwhile really only for an image that you're likely to edit again. I save most of my RAW images, so I tend not to keep an intermediate TIFF file unless I've put in a lot of work editing the image, which is really a small minority of them.

Joined: 18 Aug 2004 Posts: 15

colinml wrote:

Well, yeah, but I guess I'm asking a really basic, general question. I'm a novice, and there are so many variables I'm feeling a little frustrated. I couldn't tell a jpeg artifact from my own over-sharpening at this point, so I guess I'm just trying to figure out whether the jpeg thing is worth worrying about. How many saves is too many? I guess the file is saved when the negatives are scanned to CD, then I save it after editing, and it is saved again when it is uploaded to an on-line printing service. Are all these saves ones that result in loss? Are three saves enough to make a difference?

Thanks.

Just to clarify. You can copy a jpeg without any change at all as many times as you want. The only time you remove information or degrade the image is during a compression which happens when you make any kind of change to the original.