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PostPosted: Mon Apr 19, 2010 2:10 pm 
Hello I need some help with this programme.
After I touch up my raw pictures and want to save them into another file as jpegs, what is the best compression ratio and resolution to use as to have a good quality file if I need to make enlargments

Thanks


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PostPosted: Wed Apr 21, 2010 3:34 am 
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Unless you really need to save space, saving as JPEG is a bad idea. The JPEG format is not archival as some operating systems will degrade the photo by recompressing the already compressed image when saving the JPEG file even if you've changed nothing.

The other reason saving out to JPEG at a certain compression ratio and size is bad is that not good practice to save a corrected file for the final enlargement size, instead you should have a MASTER file that retains ALL the detail (maximum resolution & 16 bit) and then make a edited version for the particular output size or purpose. The file format that will retain the highest amount of data would be a layered 16 bit TIFF file.

If you need to conserve space but keep the original corrected/adjusted output, you can save out to png.

If space is not an issue you can save out to 16 bit tiff.

Alternatively, you can save out to 16 bit TIFF & JPEG that way you retain the highest quality edited version along with a JPEG.

Saving as format JPEG is more useful for web display not as a file format for printing from.

A general rule of thumb for printing a file is that you need between 180-480 PPI for an acceptable print, which PPI is dependent on such criteria as subject matter and viewing distance and you want have loss-less or no compression applied to the image in order to maximize output fidelity.


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PostPosted: Thu Apr 22, 2010 9:14 pm 
There's a lot of misinformation on the net about JPEGs. To put them to rest, just consider this. All the major stock photo agencies require submitted images to be JPEG. Now keep in mind two things, 1) Stock photo agencies are famous for the very high quality criteria they set and 2) Stock photos are meant to be edited. If JPEG works for these large photo agencies, it'll work without a problem for you.

As to maltau571's original question, save it at the maximum resolution (i.e. don't shrink or enlarge it) and use JPEG compression of 85% or higher.


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PostPosted: Thu Apr 22, 2010 10:30 pm 
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I use 90% compression if I save them for the web, and save as 100% for print work (just because, I never bothered to check the difference).

The main thing to keep in mind is to always keep the raw files, and never edit the Jpegs. Just edit the raw, and export a new jpeg afterwards :)

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PostPosted: Fri Apr 23, 2010 1:00 am 
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pgtips wrote:
2) Stock photos are meant to be edited. If JPEG works for these large photo agencies, it'll work without a problem for you.



An editing workflow that is only 8 bits is not sufficient for retaining the best processing. Converting to JPEG is a sacrifice. A large photo agency or not, editing a JPEG is non ideal. With the price of storage (i.e. cheap) these days it makes no sense for an end user to save only JPEGs of their hard work.

As for info on the web about, here's a good link referencing the problem with JPEG saving problem

Quote:
The quality differences are more subtle with generational losses when compared to simply picking the wrong quality level (above), but by the 10'th generation, obvious blotching and color changes are occurring.


http://www.steves-digicams.com/knowledg ... osses.html

To quote the above website's conclusion:

Quote:
What's the Bottom Line?:

The JPEG image format offers a way to save images using less space, but with some loss in image quality. Typically, a first generation save will be almost as good as a lossless TIFF as long as you use quality levels close to the highest available. Some "die hards" claim that you should never use a camera in JPEG mode when you have TIFF or RAW available as an option, and one cannot argue that you get the best quality and best editing capability with TIFF or RAW when compared to JPEG. That said, JPEG is a perfectly valid format to use even when capturing images the first time in your camera, especially when memory space, shooting speed, or the ability to print images without post processing is important. Remember that JPEG's are processed and ready to view/print, whereas RAW images require post processing to "develop" the images from the raw data. This takes additional time and can complicate your shoot-to-print workflow. A first generation JPEG will offer quality comparable to any other final or ready-to-print format, however, cannot offer latitude for correcting exposure and other shooting issues like a RAW image or a 48 bit TIFF. Bottom line: choose what works for you, but be sure to take the pros/cons of each format into consideration.



Also, here's a related article on JPEG image processing and associated limitations:
http://www.luminous-landscape.com/tutor ... lies.shtml


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PostPosted: Fri Apr 23, 2010 11:56 am 
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Capital, may I inquire if you are speaking from experience here, or just citing sources?
I'm speaking from experience here, I've never encountered problems.

the whole 8 bits? Our computer screens can actually only show 8 bits, and the same goes for paper. More bits is only useful if you heavily tweak shadows/highlights, and even then it comes down more to the sensor full-well size.

Trust me, after postprocessing, Jpeg is more than enough, for print and web display.

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PostPosted: Fri Apr 23, 2010 12:28 pm 
Please don't take this the wrong way, but you seem to be missing the point.

Nobody is arguing that when you re-save a JPEG after making adjustments, you lose some image quality as the image data gets re-quantized. The point in question is how much data you lose and whether it matters in the end. The fact that stock photo agencies and professional printers accept (many even require) JPEGs indicates that JPEGs are of good enough quality.

If you're shooting JPEG, you should treat your camera generated JPEG as if it was a film negative. That means you never save over it! You open the file, make your edits and then do a "Save As ...". Therefore, you will not encounter the quality loss of repeatedly saving a JPEG.

In maltau571's case you have a RAW file in which you've made some edits, archiving the result as a JPEG makes sense. Exporting it to a 16 bit PNG or TIFF is just a pointless waste of space.


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PostPosted: Fri Apr 23, 2010 6:29 pm 
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:)
I rather have someone know there is a choice than to think JPEG is the only option. They can elect to save as a JPEG and its inherent limitations, or save in an uncompressed higher bit depth file format. I am not sure how that is a misunderstanding, as I prefaced my initial post with "Unless you need to save the space"

Additionally, I would not be advocating for working with 16 bit files after raw processing if it did not make sense to do so. Those links are to provide information in perhaps a clearer format why do I need to retype everything out that someone else has already done.

Finally, to argue that needing only 8 bits for displaying content is inaccurate. A best practice is to edit in an environment with as high a bit depth as possible to minimize round off error when performing image manipulations. Moreover, if the source file only has 8 bits per channel of information then when newer display technologies take shape you are essentially just going to be interpolating instead of actually having more color information i.e. higher bit depth images are future looking. 10 bit (1 billion) color displays are here, but not affordable.

:)


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PostPosted: Fri Apr 23, 2010 6:51 pm 
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I think we're both missing eachothers point.

I completely agree you want to keep the most bits (within reason) for your editing workflow. However, exporting the image is not part of the editing workflow anymore, it's the finished product. ;)

Stock photos aren't very drastically edited, that's what they are stock photos for. If an agency has a specific goal in mind they hire a photographer, art director etc, they don't buy a stock photo.

Stock photos are for sticking some random multicultural people in your advertisement. :lol:

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PostPosted: Fri Apr 23, 2010 7:04 pm 
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I am not sure if the whole board is full of stock photo people :shock: , but for those who aren't stock photo people, there are alternative file formats that make sense.


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PostPosted: Fri Apr 23, 2010 11:33 pm 
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Definitely. If I had to supply my images to the magazine's photoshop artist I'm sure he would appreciate the Tiff file, in that case you are absolutely right. :)

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PostPosted: Sat Apr 24, 2010 3:28 am 
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Hello. I have just switched to Canon after several years with Olympus and have become accustomed to a workflow that involves processing the RAW files (.orf for Oly, .cr2 for Canon) through the Adobe Raw feature of Adobe Bridge in Adobe's CS4 suite.
I have not used EOS Utilities before, but at first glance see no reason to switch from Photoshop. I would really value any opinions as to why I should switch.
regards
Brian


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