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question about picture quality


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#1 shady chaaban

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Posted 27 November 2008 - 10:14 AM

i don't know if this is the proper place to post such topic, anyways help will be apreciated :)

so .. we had a project which was about shooting a movie in pictures. everything was shot with a nikon D300 uncompressed format.
i uploaded my photos on a macintosh and color corrected them. the thing is that when i saved them as .jpeg and opened them on a windows pc (since im editing on a window's avid version- obliged) i noticed a huge loss in their quality ..
i changed the mode from RGB to CMYK : same thing . noting that both pc's monitors are calibrated .
what can i do to preserve the best quality from my pictures in that case?
the whole project will be exported on a DVD.

thanks anyways ..
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#2 Evan Pierre

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Posted 27 November 2008 - 01:17 PM

I don't know much about digital photography formats but I know that JPEG is a big quality loss over RAW. I'm sorry I can't help you with what format would work better, I have no experience with that type of photography.

Best of luck!
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#3 shady chaaban

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Posted 28 November 2008 - 02:41 AM

I don't know much about digital photography formats but I know that JPEG is a big quality loss over RAW. I'm sorry I can't help you with what format would work better, I have no experience with that type of photography.

Best of luck!



yes there is a loss of quality in JPEG over RAW.. the thing is that i feel there's a loss in macintoshs' JPEG and windows' ..
thanks anyways :D ... it's probably not the correct place for such topic
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#4 Andrew Koch

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Posted 28 November 2008 - 05:07 AM

jpeg is a highly compressed format. Once you color correct your raw file, consider saving it as a tiff file instead. You should have an option to set the compression quality as well. The higher the quality, the larger the file. So all you need to do is balance out how much quality you want with how much space you have.
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#5 wolfgang haak

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Posted 30 November 2008 - 08:47 PM

i changed the mode from RGB to CMYK : same thing . noting that both pc's monitors are calibrated .
what can i do to preserve the best quality from my pictures in that case?
the whole project will be exported on a DVD.

thanks anyways ..


Shady,
I'm gonna delve right in:

Calibration. Are the monitors calibrated or profiled? Notice that most "calibration" devices available for PCs/Mac are actually only profilers. The tell you how you monitor responds to a signal. It does not affect the way it displays a signal.
Packages like photoshop will use profiles to alter the signal they send to the monitor, as they know how the monitor responds. The actual colour info for each pixel, is adjusted by a LUT (Look Up Table) or ICC Matrix to find the new value that has to be send to the monitor. It adds the "error" of the display as an offset to the signal it send to it in order to achieve the colour that you expect to see. This technique is very error prone, as there's no limit to the degree of modification in the LUT/Matrix. With monitors, where the hardware whitepoint and gamut range (amongst other values) are miles apart, expect to see colour banding, colour clipping and clamped areas (looks like a solarisation in strong hues) etc.
What is the calibration target of you displays? If the calibration target of your display is miles out from the display hardware settings and different from the image colour space it's not gonna look pretty no matter what you do. See below under "Colour Space" dog-to-cat conversion.
Is you software set up right?
Check your colour settings. In the CS versions of photoshop edit -> colour settings. Select "preserve embedded profiles" on all three tick boxes. (and check all the warning box messages as well.)

Colour Space:
Sorry mate, what? CMYK is a four colour process intended for offset printing presses by splitting the image into its four ink plates. No-no-no for what you are doing. Have a consistent colour workflow and avoid every unnecessary conversion.
How did you "change" the mode? Edit-> Assign Color Profile, or Edit->Convert to profile? If you're unsure about ICC profiles, the rule of thumb is never "assign" a profile. It's like telling a dog to behave like a cat. You can convert a dog into a cat, but as you can imagine it's a non-reversible action that inflicts a reduction of quality.
Compression.
Each open and save on a jpg will result in a degradation of quality. Don't believe it? Take any picture, open and save it a few times on highest settings. Watch the file size decrease each time.
choose tif format. tick embed profile, LZW compression (which is lossless).
hope this helps a bit!
regards,
Wolfgang
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#6 Paul Bruening

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Posted 30 November 2008 - 08:55 PM

Wolfgang,

Good answers. Right on the money. I was just about to post the same stuff. Good thing I rechecked before posting. I would have looked goofy saying the same thing two minutes right after you. I love TIFFs from RAW. They're as big as Texas but very versatile. One of the guys here went to Targa file format and seemed to be getting good results. I haven't worked in Targa for 10 years or more. Targa and VRML.
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#7 Alfeo Dixon

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Posted 30 November 2008 - 09:55 PM

Very Nice Wolfgang... one thing he left out, once you color correct, then save down to the resolution you will be working with as an end result. Your editing system will thank you.

RAW uncompressed once opened in photoshop will sometime double in size with is still WAY too much information than your ever going to deal with. I would shoot uncompressed RAW (D1x/D2/D3/D200/D300) on features as a stillsman and still had studio's like ABC asking for Jpegs, simply because they didn't want to spend too much time pushing these large amounts of pixels for something that would never see past a 5x7 in a magazine.

Paul... Targa... Wow! That takes me back.
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#8 wolfgang haak

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Posted 01 December 2008 - 07:27 AM

Paul,

be careful with those tga images. The TGA wrapper does not support embedding of profiles, so you will have to guess and assign one each time you open the image. Near impossible to keep on top of!
That's why Tifs a a good general purpose choice!
- lossless compression
- embedded profiles
- 8 and 16 bit per channel,
- multilayer
- alpha channel
...

Wolfgang
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