Luminous Landscape Forum
Raw & Post Processing, Printing => Digital Image Processing => Topic started by: Sam Chapman on March 02, 2015, 07:54:05 pm
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If I have a RAW image which I know is going to require some pretty extensive editing, (more sophisticated than can be done to a RAW image) instead of converting the file straight away as a JPEG, then editing and saving that, will I get significantly better results if I first make a copy of the RAW file as a TIFF, carry out all the work that needs to be done on that TIFF file, and when I have got everything as I want it, then save another version of this final image, as a JPEG?
I realise that each time you open and save a JPEG during extensive editing, (because it's a 'Lossy' file format) you are likely to degrade the quality of the image file, and a TIFF file does not suffer from this issue, but what I don't think I've ever seen anyone comment on, is how great a benefit one is likely to gain, from editing the file as a TIFF, and then once you have completely finished all your editing and resizing etc, saving that file as a JPEG. Does anyone here use this method?
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I'd consider JEPG an output specific kind of file format. I want something I can post to the web, it doesn't need to be large, high bit, wide gamut etc. So about the only time I move from raw to JPEG (or TIFF to JPEG) is when I know the size, and output specifics of the JPEG to build for that use.
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Thanks for the reply, but it doesn't actually answer the question I asked. I do want the finished file as a JPEG, it's just that I am wondering if by doing all of the editing on the file, as a TIFF and then finally saving that as a JPEG, is going to deliver significantly better results than carrying out all the same processing on a JPEG file? I am thinking that because the TIFF file has a much wider range of colours, and it's also a lossless file format, the impact of any editing done, is going to be less pronounced (unwanted artifacts-wise) when it's finally converted over to a JPEG.
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... I am wondering if by doing all of the editing on the file, as a TIFF and then finally saving that as a JPEG, is going to deliver significantly better results than carrying out all the same processing on a JPEG file?..
Yes.
You seem to be arguing with yourself, as you are actually providing in your posts all the good reasons to stay in TIFF as long as possible (except, perhaps, forgetting the main one: 16 bit vs. 8 bit editing).
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… how great a benefit one is likely to gain, from editing the file as a TIFF …
… I am wondering if by doing all of the editing on the file, as a TIFF and then finally saving that as a JPEG, is going to deliver significantly better results …
Why do you care? The only cost you're likely to notice is more disk space used, so just save-as tif and make your edits.
(I use RawTherapee and save-as tif both for processing in other software and for archive.)
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Sam, the general rule is to edit as a raw file as long as possible.
If you need to convert to a TIFF file then make sure it is a 16-bit conversion.
As Andrew Rodney has already stated a JPEG is just an output-specific derivative file.
If you care at all about image qualtiy do not edits on a JPEG.
Forget about lossy compression for a while and consider that a JPEG is an 8-bit file - both tone and colour will be adversely affected with any editing apart from the most subtle.
You have not enlightened us as to why you cannot edit predominantly as a raw file - my guess is that much more can be done than is apparent to you.
Perhaps if you share more about your workflow and the rationale behind it collectively we can better help you.
Tony Jay
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If I have a RAW image which I know is going to require some pretty extensive editing, (more sophisticated than can be done to a RAW image)
I quite don't understand that part of the question.
If the editing can be done totally by Lightroom, then there is never any need to save from Raw in any other format until eventual Export as a Jpeg (or whatever).
If additional editing is required (say in CS6 or CC or Nik or Topaz) then that can be done from within Lightroom and the edited image will be saved back into LR as a Tiff (next to the Raw in the filmstrip unless you specify differently).
Either way, your Raw file is never altered. and, if a Tiff has been created, you can Export from the Tiff to a Jpeg as the final step in your workflow.
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Thanks for the reply, but it doesn't actually answer the question I asked. I do want the finished file as a JPEG,
I think he did answer the question ... a jpeg is only an output specific file, another term used by many is a "purposed" file. So the answer is not to save you "final" file as a tiff.
My question is why do you want the "finished file as a JPEG?" I would never do this
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Much depends on the destination and use of the image. If it will be printed large on a high quality inkjet, 16 bit tiff will allow you to stay in a wide gamut space and not lose colors of which the printer is capable. If it is destined to be no more than a 800x1200 pixels sRGB posted on the web, you might as well go directly to jpg, the losses won't be visible anyways.
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If I have a RAW image which I know is going to require some pretty extensive editing, (more sophisticated than can be done to a RAW image) instead of converting the file straight away as a JPEG, then editing and saving that, will I get significantly better results if I first make a copy of the RAW file as a TIFF, carry out all the work that needs to be done on that TIFF file, and when I have got everything as I want it, then save another version of this final image, as a JPEG?
I realise that each time you open and save a JPEG during extensive editing, (because it's a 'Lossy' file format) you are likely to degrade the quality of the image file, and a TIFF file does not suffer from this issue, but what I don't think I've ever seen anyone comment on, is how great a benefit one is likely to gain, from editing the file as a TIFF, and then once you have completely finished all your editing and resizing etc, saving that file as a JPEG. Does anyone here use this method?
Yes, pretty much everyone who is at all familiar with photo editing and file formats. You should be creating jpegs only for final use, such as posting on the web or sending in an email. Use a 16 bit TIFF for best results.
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When digital was a new thing our publishing company ran a test where JPEG files were opened, slightly edited and saved. After 7 iterations slight changes became noticeable to professionals on a printed spread. On a fine art print it might show up sooner, so editing TIFFs is the right solution, but there is no reason to worry too much about editing a maximum quality JPEG a few times if that is all you have.
At least with my laptops TIFF does have a speed penalty, TIFF with few layers might be over 200 MB, while JPEG is 15MB or so. I do 80-90% of adjustments in LR before conversion and export JPEGs, unless I know I will manipulate a file in PS for high-resolution printing, then TIFF. For magazine publishing JPEG is good enough.
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Why not save as .psd?
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Why not save as .psd?
No reason to. It's a proprietary file format and there is nothing PSD provides (other than duotone) a TIFF can't provide. TIFF like JPEG is an open format, no licensing fee for any software company to use, hence you'll find far more products that can support TIFF than PSD.
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If I have a RAW image which I know is going to require some pretty extensive editing, (more sophisticated than can be done to a RAW image) instead of converting the file straight away as a JPEG, then editing and saving that, will I get significantly better results if I first make a copy of the RAW file as a TIFF, carry out all the work that needs to be done on that TIFF file, and when I have got everything as I want it, then save another version of this final image, as a JPEG?
I realise that each time you open and save a JPEG during extensive editing, (because it's a 'Lossy' file format) you are likely to degrade the quality of the image file, and a TIFF file does not suffer from this issue, but what I don't think I've ever seen anyone comment on, is how great a benefit one is likely to gain, from editing the file as a TIFF, and then once you have completely finished all your editing and resizing etc, saving that file as a JPEG. Does anyone here use this method?
I don't know exactly how the RAW developer you are using might operate, but if after developing the RAW file, it opens the developed file into Photoshop, then it doesn't really matter as long as you do all the editing before saving it out. The data being operated on is different than the data saved into a JPEG file. JPEG lossy compression only comes into play when saving the file out to disk. If your RAW developer on the other hand saves out the developed RAW to a file 1st, then yes it matters because the lossy compression will have operated on the file data.
However, you would probably want to use a TIFF or PSD file as an intermediary as you might continue to tinker or later want to re-purpose the image. Then save out the final purposed image as a JPEG.
[ADDED] Oh, and using JPEG is not bad or anything to be ashamed of. As long as the image is not resaved over and over again and the compression is not pushed to significant levels, JPEG files are virtually indistinguishable from a similar bit depth TIFF. I shoot JPEG, NEF 12 bit Lossless Compressed and NEF 14 bit Lossless Compressed depending on the requirements for the image and the lighting conditions. There are reasons to be anal from capture through to output when required to get everything you can, especially when significant scaling or editing is in the cards, but be wary of advice that you always have to do something some particular way. But you can get caught with your pants down if you are lax with an image intended for screen and then someone wants a large printed version.
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As long as the image is not resaved over and over again and the compression is not pushed to significant levels, JPEG files are virtually indistinguishable from a similar bit depth TIFF.
Saving a JPEG over and over again doesn't alter quality as long the compression rate is kept. I guess the algorithm just saves back the same RGB numbers again and again.
Unfortunately the sample images are lost because I uploaded them to imageshack in 2006; I opened and saved a JPEG file (introducing slight edit changes in some very specific pixels everytime leaving the rest unaltered) 2000 times, and the quality of the 2000th copy was indistinguishable from the original JPEG.
When the changes consisted in rotations quality degraded very quickly though.
Regards
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In some cases (like high contrast lettering) JPEG can show compression artifacts even at the highest quality level. That shows up very rarely and only at large magnifications. I use TIFF only for exhibition prints, for everything else JPEG at max quality is more than fine.
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Saving a JPEG over and over again doesn't alter quality as long the compression rate is kept. I guess the algorithm just saves back the same RGB numbers again and again.
Unfortunately the sample images are lost because I uploaded them to imageshack in 2006; I opened and saved a JPEG file (introducing slight edit changes in some very specific pixels everytime leaving the rest unaltered) 2000 times, and the quality of the 2000th copy was indistinguishable from the original JPEG.
When the changes consisted in rotations quality degraded very quickly though.
Regards
I wonder if your editing wasn't enough to kick in the jpeg compression Guillermo? Or the changes weren't global hence the compression wasn't global? Here's an approx 1:1 from some years ago. Left side the original, right the jpeg after 26 saves with a minimal work done, and undone the next iteration. I don't think you'd ever see any change after 6 or 7 saves, but I wouldn't want to go much farther.
David
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Yes, they were not global changes, just added a new pixel in a diagonal line on every iteration. The final image only differed in the NxN pixel blocks surrounding the modified pixels.
When global changes were applied I recall degradation was easily visible.
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Saving a JPEG over and over again doesn't alter quality as long the compression rate is kept. I guess the algorithm just saves back the same RGB numbers again and again.
Yes, the JPEG algorithm looks at the data and calculates the same file given the same data. I was thinking more of as the image is EDITED and then resaved.
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I think he did answer the question ... a jpeg is only an output specific file, another term used by many is a "purposed" file. So the answer is not to save you "final" file as a tiff.
My question is why do you want the "finished file as a JPEG?" I would never do this
I like to refer to my jpg as a "distribution file" It is NOT the medium I use to process an image, or even store my 'done' photos. I like to work on and store my images after raw processing as 16 bit color depth tif files. To me, the only negative of using Tif is the large size, and that isn't the issue it used to be.
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Saving a JPEG over and over again doesn't alter quality as long the compression rate is kept. I guess the algorithm just saves back the same RGB numbers again and again.
I don't believe this is true. I ran a test where I opened a TIFF, saved it as JPEG with Photoshop quality 8. I then closed the file, re-opened the just-saved jpg, "saved as" another jpeg with the same quality and new name, and repeated 4 times. The file sizes were:
Iteration 1: 1695 kb
2: 1670
3: 1668
4: 1669
The slight size increase at iteration 4 is a bit of a mystery, but you can see the file size goes down with each re-saving of the file (no changes were made to the image). Something is being lost.
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I don't believe this is true. I ran a test where I opened a TIFF, saved it as JPEG with Photoshop quality 8. I then closed the file, re-opened the just-saved jpg, "saved as" another jpeg with the same quality and new name, and repeated 4 times. The file sizes were:
Iteration 1: 1695 kb
2: 1670
3: 1668
4: 1669
The slight size increase at iteration 4 is a bit of a mystery, but you can see the file size goes down with each re-saving of the file (no changes were made to the image). Something is being lost.
I'm not convinced the difference in the numbers are big enough to indicate jpeg compression is kicking in. It could be due to the file name changing or some other factor.
I just ran the same test with a tiff. Opening and saving with an added underscore and number. The file sizes were:
1: 63,115,564 bytes
2: 63,116,452 bytes
3: 63,117,312 bytes
David
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I ran a test where I opened a TIFF, saved it as JPEG with Photoshop quality 8. I then closed the file, re-opened the just-saved jpg, "saved as" another jpeg with the same quality and new name, and repeated 4 times.
I did the same test. But I used Calculations (Subtract) on JPEG 1 vs. JPEG 4 and they are identical.
If we alter the image then re-save, then I'd expect to see differences. But a Save As... multiple JPEG produces the same JPEG on this end.
JPEG 1 is 613KB while JPEG 4 is 608KB so the Mac Finder isn't a good indicator of the data differences.