JPEG Files: Keeping Originals
I'm confused about when jpeg files degrade.
I shoot photos in high quality jpeg format. Using a card reader, I download a copy of the whole card in jpeg format onto an external hard drive. They don't get edited or reduced---just copied. For processing, I download a second copy of the whole card in jpeg format onto my hard drive.
At that point, I review the thumbnails in the browse feature of PaintShop Pro 9. I may open a few of them, but I don't rotate them or do anything else. I delete any that are obviously bad. Then I do a batch conversion of the jpegs into psp files for processing.
Here are my two questions:
1. Once in awhile, I mistakenly save a change to the newly converted psp file. That's when I go back to my "negatives" to make a new psp file for editing. When I open and copy a jpeg file, is that an editing process? Am I introducing loss into the original or the new psp file that I make from it?
2. If simply copying a jpeg file does not introduce loss, what's wrong with keeping my "negatives" in jpeg format? They sure take up a lot less space.
Thank you very much for any insight you can offer.
Re: JPEG Files: Keeping Originals
I have been saving to high quality JPEG, too. Then cropping and resaving. The JPEG from the camera is the sensor data with post processing. RAW is sensor data. I would expect the camera is using compression to reduce the file size, and introduces some loss. Saving the file again with compression would most likely introduce some degregration. This is a question I still have.
I can save the opened file without compression (lossles). The camera must be about 6:1. What happens if I save to the same compression?
No idea what happens when PSP saves to its format.
Rich
Re: JPEG Files: Keeping Originals
soenda,
Any type of image file will lose data when you run filters on it - or directly adjust it's appearance (colour, shapness etc...) Therefor use adjustment layers when possible. Data is also discarded when "image data" is saved to a lossy image format such as a .jpg again (even at 100%).
.jpg (lossy) ---> brought into Photoshop .psd (lossless as Photoshop Data - unless you manipulate the data/adjust the image directly) ---> saving to .jpg again (you lose data again).
You can save a .psd or .psp file a million times without affecting the quality (if you also don't adjust/change the image data). Adjusting adjustment layers doesn't effect the quality.
Once a .jpg file is brought in to Photoshop or Paint Shop Pro it no longer is a .jpg file anymore - it's just data.
soenda, you don't lose data by opening a file. You also don't lose data by copying a file from one location to another - or making any number of copies of the file. Again, you only have loss when you manipulate the actual data (or save it again as a lossy image format because of the compression).
As for keeping your "negatives: in .jpg format - why not? If it does the trick for you... However, if you have a good camera (or any camera...) that can create files in more than 8-bit RAW, it's technically sounder to keep them as RAW files as they contain more data (that you can manipulate).
Risto
Re: JPEG Files: Keeping Originals
Quote:
Originally Posted by
soenda
I'm confused about when jpeg files degrade.
I shoot photos in high quality jpeg format. Using a card reader, I download a copy of the whole card in jpeg format onto an external hard drive. They don't get edited or reduced---just copied. For processing, I download a second copy of the whole card in jpeg format onto my hard drive.
At that point, I review the thumbnails in the browse feature of PaintShop Pro 9. I may open a few of them, but I don't rotate them or do anything else. I delete any that are obviously bad. Then I do a batch conversion of the jpegs into psp files for processing.
Here are my two questions:
1. Once in awhile, I mistakenly save a change to the newly converted psp file. That's when I go back to my "negatives" to make a new psp file for editing. When I open and copy a jpeg file, is that an editing process? Am I introducing loss into the original or the new psp file that I make from it?
2. If simply copying a jpeg file does not introduce loss, what's wrong with keeping my "negatives" in jpeg format? They sure take up a lot less space.
Thank you very much for any insight you can offer.
It seems to me that if you do not save the file with the JPEG extension, you haven't altered the original jpeg. If you check the file dates on the jpeg, you'll see that opening them does not change them UNLESS you resave it as a JPEG under the original name.
My camera does the same as yours does. I have all my originals in a "negatives" folder, and when I first open any of them, either to work on them or print them, I immediately save them as a psimage file in another folder before doing anything else.
That little habitual protocol maintains the originals in their virginal and unsullied state, safe in the "negatives" folder cloister :D
Regards,
Alan
Re: JPEG Files: Keeping Originals
a brief summary of lossless editing here: [section 1.5]
http://en.wikipedia.org/wiki/JPEG
Re: JPEG Files: Keeping Originals
Whenever you save a JPEG you'll lose data, because with every save there is compression.
In order to avoid this, save the file in a lossless format, such as PSP's native .psp or .pspimage (which allows you to keep all your layers for example), TIFF or PNG.
Re: JPEG Files: Keeping Originals
Okay, I am feeling like the Bear with Very Little Brain. May I try to play back what I've understood, to see if it crossed the confusion barrier? :o
1. If I run PSP's batch conversion on my newly downloaded jpeg files, I am not opening and resaving the jpeg, so no loss is introduced to the jpeg file.
2. If I need to go back to my "negative" copy, open it and make a second copy of it, that still does not constitute an editing or saving action, so the jpeg is unaltered.
3. As I review the newly uploaded jpegs (this is the second batch, the one that I took from the card reader and copied onto my hard drive), I can open the jpeg file, then close it---without rotating it or editing it in any way---and it will still be in its pristine condition because I didn't save it. Closing a jpeg and saving a jpeg are two different operations.
I'd appreciate it very much if anyone could confirm that I "got" what you've said, or set me straight if I didn't. This is enormously helpful, because I have been making mistakes in overhandling jpeg files AFTER processing them in PSP and reconverting them to jpegs for posting on forums.
Thank you very much for your gracious assistance.
Re: JPEG Files: Keeping Originals
Quote:
Originally Posted by
handrawn
Aha--I should have known! It's all about rounding errors in the end!
Thank you very much for the link to the article. As I saw the matrices swimming toward me on the screen I thought I was done for, but I found my footing again by the end of the article.
Re: JPEG Files: Keeping Originals
Quote:
Originally Posted by
molucca
I have been saving to high quality JPEG, too. Then cropping and resaving. The JPEG from the camera is the sensor data with post processing. RAW is sensor data. I would expect the camera is using compression to reduce the file size, and introduces some loss. Saving the file again with compression would most likely introduce some degregration. This is a question I still have.
I can save the opened file without compression (lossles). The camera must be about 6:1. What happens if I save to the same compression?
No idea what happens when PSP saves to its format.
Rich
One of the messages in the Wiki article seems to be that cropping a jpeg, except under certain specific conditions or while using special applications, can introduce loss. It seems counterintuitive, but I think it's one of the mistakes I had been making after processing photos as psp files and converting them back to jpegs. If I understand correctly, unless you have an application specifically for loss-lessly cropping jpegs, you should go back to the editing format---psp, tif, or whatever, to do further adjustments like cropping.
But I'm easily confused, and I could be wrong.
As for the whole compression issue---I'm still working on trying to figure that one out. :o
Re: JPEG Files: Keeping Originals
Quote:
Originally Posted by
Risto Klint
soenda,
soenda, you don't lose data by opening a file. You also don't lose data by copying a file from one location to another - or making any number of copies of the file. Again, you only have loss when you manipulate the actual data (or save it again as a lossy image format because of the compression).
As for keeping your "negatives: in .jpg format - why not? If it does the trick for you... However, if you have a good camera (or any camera...) that can create files in more than 8-bit RAW, it's technically sounder to keep them as RAW files as they contain more data (that you can manipulate).
Risto
Thank you for your detailed explanation. Unfortunately, RAW is not an option on the camera I use---Panasonic FZ7---plus, as a relative beginner, I tend to take lots of shots in each session, varying things like f-stop and ISO sensitivity. I use a 2-Gig card, which allows me to bring home 340+ high quality jpeg files per session. I'm afraid that if I was shooting RAW files, I'd use up the card space so much more quickly, it would be like going back to film...at least that's my current impression.
I really appreciated your reassurance about being able to save and resave. Thanks.
Re: JPEG Files: Keeping Originals
The non-technical reason why there is loss when you save in jpeg format is because a higher priority is given to keeping the file size low. This so high quality images could be put on the web that loaded up quickly. It was always meant to be a 'one-off' operation - It is not a storage format IMO.
No problem with the originals ['negatives'] in jpeg, but if you need to make changes, I'd then store them in a different format that is lossless, as Risto and others have said
:)
Re: JPEG Files: Keeping Originals
Quote:
Originally Posted by
soenda
One of the messages in the Wiki article seems to be that cropping a jpeg, except under certain specific conditions or while using special applications, can introduce loss. It seems counterintuitive, but I think it's one of the mistakes I had been making after processing photos as psp files and converting them back to jpegs. If I understand correctly, unless you have an application specifically for loss-lessly cropping jpegs, you should go back to the editing format---psp, tif, or whatever, to do further adjustments like cropping.
But I'm easily confused, and I could be wrong.
As for the whole compression issue---I'm still working on trying to figure that one out. :o
Well you can not crop losslessly as cropping cuts of some of the image, but if you save as jpeg then depending on how much compression is used then some pixels are noted as to there position and colour the discarded. Hence the lose. When the image is opened those pixels are painted in but are not the original. doing this over and over will gradually produce rubbish. So save your originals in a save place and even mark as read only if you want the only work on a copy after all your enhassment you could save it in lossless format PSP, PSD, Tiff or png Ect. and then do a resize if need be and save as .jpeg for the web. And incidentally rotating a jpeg by increments of 90 degrees is lossless as no pixels are changed only resorted.
Re: JPEG Files: Keeping Originals
Quote:
Originally Posted by
Trev
Well you can not crop losslessly as cropping cuts of some of the image, but if you save as jpeg then depending on how much compression is used then some pixels are noted as to there position and colour the discarded. Hence the lose. When the image is opened those pixels are painted in but are not the original. doing this over and over will gradually produce rubbish. So save your originals in a save place and even mark as read only if you want the only work on a copy after all your enhassment you could save it in lossless format PSP, PSD, Tiff or png Ect. and then do a resize if need be and save as .jpeg for the web. And incidentally rotating a jpeg by increments of 90 degrees is lossless as no pixels are changed only resorted.
So you really can rotate the jpegs 90 degrees without loss? Cool! I saw this as I was researching the whole lossy jpeg issue before I posted my original question. But I put it in the "too good to be true" category.
It would save a lot of time if I could batch rotate all my portrait format shots on my first pass of the jpeg files. I generally look for duds before doing the conversion to psp files, but sometimes without rotating the file I can't tell the keepers from the tossers. If there's no loss from 90 degree rotation, then I won't waste time converting duds I could eliminate as jpegs.
Thanks very much, Trev.
Re: JPEG Files: Keeping Originals
Quote:
Originally Posted by
handrawn
The non-technical reason why there is loss when you save in jpeg format is because a higher priority is given to keeping the file size low. This so high quality images could be put on the web that loaded up quickly. It was always meant to be a 'one-off' operation - It is not a storage format IMO.
No problem with the originals ['negatives'] in jpeg, but if you need to make changes, I'd then store them in a different format that is lossless, as Risto and others have said
:)
Thanks, Hand. Actually, I do keep an archival copy of all the files newly converted from jpeg to psp.
When I choose images to edit, I save a new copy and rename the file. That way I have two backups in pristine condition. My "negatives"---the jpegs straight from the card reader, and the psp files directly from the conversion.
The jpeg negatives offer me insurance so that if I accidentally save changes I've made to the new psp files, I can make a new "original psp" from the negatives.
That's why this thread has been so helpful to me. Now I'm not afraid of reopening the negative file jpegs for making those replacements for "oops" mistakes.
I'm really grateful for your time and thought.
Re: JPEG Files: Keeping Originals
you got some great photos there soenda - being a bit of a horse freak myself I particularly liked the 'flirtatious' and the 'sign? what sign?', that ones just ace!
:D
Re: JPEG Files: Keeping Originals
Quote:
Originally Posted by
soenda
It would save a lot of time if I could batch rotate all my portrait format shots on my first pass of the jpeg files.
The free image viewer IrfanView is able to rotate your JPEG files losless:
- Start IrfanViews thumbnail viewer
- Select all the files you want to rotate
- Press "Shift+J" and select the option "Auto-Rotation (by EXIF information)" and IrfanView interpretes the rotation information, saved by your digital camera within the JPEG file and rotates all your images into the right angle (horizontal to vertical or vertical to horizontal) - losless.
Regards,
Remi
Re: JPEG Files: Keeping Originals
personally, I would save in a format such as TIFF. This is an uncompressed format and it's format can be used on any PC/MAC. By saving proprietary formats such as PSP, you limit its use to PC's that have the software installed, unless converted to a more common format. Also, what if you change software down the road?
I would only save in this proprietary format if I have done a lot of post processing or have created several layers and may return to it often to keep making changes or even undo changes.
On the JPEG loss issue, You have to save the same JPEG many many times to see real degredation in image quality. However, it does depend on how much postprocessing that was done and the quality of the original image.
Those that have the option to shoot in the RAW (albeit, proprietary as well) format, In my opinion, this is the best Archival solution. Convert to JPEG's when you want to use them. Most RAW processing software never alters the original RAW file. They are much smaller than TIFF's or proprietary files (PSP) and you're guaranteed the highest quality image your camera can produce.
Re: JPEG Files: Keeping Originals
Quote:
Originally Posted by
soenda
Okay, I am feeling like the Bear with Very Little Brain. May I try to play back what I've understood, to see if it crossed the confusion barrier? :o
1. If I run PSP's batch conversion on my newly downloaded jpeg files, I am not opening and resaving the jpeg, so no loss is introduced to the jpeg file.
2. If I need to go back to my "negative" copy, open it and make a second copy of it, that still does not constitute an editing or saving action, so the jpeg is unaltered.
3. As I review the newly uploaded jpegs (this is the second batch, the one that I took from the card reader and copied onto my hard drive), I can open the jpeg file, then close it---without rotating it or editing it in any way---and it will still be in its pristine condition because I didn't save it. Closing a jpeg and saving a jpeg are two different operations.
I'd appreciate it very much if anyone could confirm that I "got" what you've said, or set me straight if I didn't. This is enormously helpful, because I have been making mistakes in overhandling jpeg files AFTER processing them in PSP and reconverting them to jpegs for posting on forums.
Thank you very much for your gracious assistance.
What do you mean by referring to your brain as "little brain"? Your questions show that you're plenty bright enough to ask a lot of questions and analyze. No one can count that as stupid.
Try this:
- Open one of your "negatives," i.e., a JPEG
- Immediately go to FILE and click on that
- Then click on the SAVE AS option from the drop-down list
- A dialog comes up with two boxes you can enter text in, FILE NAME and SAVE AS FILE TYPE. Click on the drop down next to FILE TYPE.
- Select PSPIMAGE or PSP (or any other lossless format)
You have just saved the file without disturbing the original JPEG. Do that every time you open the original JPEG without fail. Do not save it as a JPEG with the same name.
After you have finished tarting up the photo, you can export it or save it as a JPEG, but use a different name than the original "negative's" name.
Give us a holler if you need more clarification.
Re: JPEG Files: Keeping Originals
Quote:
Originally Posted by
Crypto
personally, I would save in a format such as TIFF. This is an uncompressed format and it's format can be used on any PC/MAC. By saving proprietary formats such as PSP, you limit its use to PC's that have the software installed, unless converted to a more common format. Also, what if you change software down the road?
I would only save in this proprietary format if I have done a lot of post processing or have created several layers and may return to it often to keep making changes or even undo changes.
On the JPEG loss issue, You have to save the same JPEG many many times to see real degredation in image quality. However, it does depend on how much postprocessing that was done and the quality of the original image.
Those that have the option to shoot in the RAW (albeit, proprietary as well) format, In my opinion, this is the best Archival solution. Convert to JPEG's when you want to use them. Most RAW processing software never alters the original RAW file. They are much smaller than TIFF's or proprietary files (PSP) and you're guaranteed the highest quality image your camera can produce.
You make an extremely good point about the long term bet I'm making by saving psp files as archives. I'm old enough to remember Betamax video and even 8-track tape. Ouch. This I gotta think about.
I was surprised to see you say that RAW files are much smaller than TIFFs or psp files. I was under the impression that they were very much larger. In fact, that understanding had been part of my reluctance to bite the bullet and move up to a fancier camera. I do all my editing on a five-year-old laptop, and I thought it would choke on RAW files. This certainly encourages me to find out more about it. I understand that RAW files offer infinitely more opportunity to correct for things like white balance, which would be very nice indeed.
Thank you once again, Crypto. I should be anteing up tuition credit fees for the education I'm getting. (Please don't hold me to it, though. I'll be your first student AND your first drop out.):D
Re: JPEG Files: Keeping Originals
Quote:
Originally Posted by
alanstancliff
What do you mean by referring to your brain as "little brain"? Your questions show that you're plenty bright enough to ask a lot of questions and analyze. No one can count that as stupid.
Try this:
- Open one of your "negatives," i.e., a JPEG
- Immediately go to FILE and click on that
- Then click on the SAVE AS option from the drop-down list
- A dialog comes up with two boxes you can enter text in, FILE NAME and SAVE AS FILE TYPE. Click on the drop down next to FILE TYPE.
- Select PSPIMAGE or PSP (or any other lossless format)
You have just saved the file without disturbing the original JPEG. Do that every time you open
the original JPEG without fail. Do not save it as a JPEG with the same name.
After you have finished tarting up the photo, you can export it or save it as a JPEG, but
use a different name than the original "negative's" name.
Give us a holler if you need more clarification.
Thank you, Alan. You're very kind. I'm sure my brain is pretty much the same size it's been for the past several decades. About its density, I'm not as confident. I think there may be bubbles of emptiness forming.
But I very much appreciate that step-by-step approach you've provided in your reply. It works very well in helping me master the concept and the operation when I can go through the motions.
One more quality of understanding control check: I could open the negative jpeg file, choose "Save As" and make a second jpeg with a different name, and there would be no loss between the first jpeg and the second. The loss comes from re-saving the first or any subsequent jpeg file, as opposed to saving a copy of it. I think that I've got that right, now.
In fact, I have "Save As" as a permanent tool bar option. That's exactly what I use when I am switching a file from one format to another.
So now that it seems like I'm getting squared away on the lossy vs loss-less formats, I'm going to try to tackle the issue of resolution and resizing images for posting on Internet forums. But first I want to do a little homework so that I ask good questions, not silly ones.
Many thanks to you, Alan, and everyone here who's been so patient and generous in helping me learn. :D
Re: JPEG Files: Keeping Originals
Quote:
Originally Posted by
soenda
You make an extremely good point about the long term bet I'm making by saving psp files as archives. I'm old enough to remember Betamax video and even 8-track tape. Ouch. This I gotta think about.
I was surprised to see you say that RAW files are much smaller than TIFFs or psp files. I was under the impression that they were very much larger. In fact, that understanding had been part of my reluctance to bite the bullet and move up to a fancier camera. I do all my editing on a five-year-old laptop, and I thought it would choke on RAW files. This certainly encourages me to find out more about it. I understand that RAW files offer infinitely more opportunity to correct for things like white balance, which would be very nice indeed.
Thank you once again, Crypto. I should be anteing up tuition credit fees for the education I'm getting. (Please don't hold me to it, though. I'll be your first student AND your first drop out.):D
RAW files on my Canon 30D (8 megapixel) come to 7-10MBs. JPEGS out of the camera average 4-7MB's. RAW Conversions to PSP, TIFF's and other uncompressed files average around 50MB's. HUGE difference. Some often don't realize that a RAW file is compressed with a special algorithm that maintains image quality.
Issues with RAW files mostly come with managing them and post processing. I found the hardest part to get used to is using windows explorer to view thumbnails. RAW files cannot be viewed in windows without a special RAW Image thumbnail viewer (Powertoy from Microsoft), however, it's not updated with the latest RAW image files.
I use the explorer to help me catogorize and file images (Birds, People etc). This is easy if you can view the thumbs.
Photoshop,Lightroom, Paintshop and other postprocessing tools receive frequent updates to support the latest RAW files.
With all that said, I find the software that came with my Canon to very effective at processing RAW and manageing. Don't be affraid of RAW, it provides incredible flexibility in saving that perfect shot where you didn't quite have the camera set right and best of all, it can maintain image quality (with in reason of course).
good luck
