colour space matters
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pxl8
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Ok, dragged both into photoshop - they look identical in there because it's colour managed. First is sRGB and second is AdobeRGB - the reason for the difference is that most PC browsers aren't colour managed and won't take any notice of embedded profiles. Safari for Windows is about the only browser that will.
...and that probably shows my level of understanding of colour spaces...
There is a lot for me to learn but this quick experiment demonstrates that it does make a difference, and therefore is probably worth learning.
Boon said:
Well I shot in RAW, then exported from Lightroom, selecting Prophoto RGB (I understand this is the best one to do PP with). Then in photoshop I converted one copy to sRGB and the other copy to adobe98 and saved each. There was no difference viewing them in Windows Explorer, but when I uploaded them to the flickr, the difference became apparent.
I understood that sRGB was the one to use if they were to viewed on the net, so I was expecting a slight difference, but not quite as dramatic as this. Everything is so much more vibrant in sRGB. Actually, technically I suppose it is less vibrant in the adobe98 space (since in theory the colours in the sRGB are the correct colours).
natjag said:
That's interesting
pxl8
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The AdobeRGB looks less saturated because the colour space offers greater saturation than sRGB. So a red value of 192 would look more saturated in sRGB but ONLY if the software displaying the image isn't colour aware.
A colour aware program will translate the colours in the image so they are correctly rendered on the output device (screen or printer). Without that translation the colours you see are just plain wrong. But that's only part of the story. If you don't have a good profile attached to the output device (either through calibration or by using one supplied with the device) the rendered colours will still be wrong but probably in a different way.
Think of it in terms of language so:
sRGB=English
AdobeRGB=French
ProPhoto=Latin
Output Device=German, Italian, Spanish, etc.
To get accurate colours you need to translate to the output device - which (in terms of sRGB) might be close to English but with a strong regional accent affecting the results. Most Windows applications don't do any translating and some that do will still screw it up at some point - printing from Corel PaintShopPro for example.
If you're using ProPhoto as a working space for your image then be warned that unless you work in 16bit and can output to a device that natively supports 16bit you will probably be worse off with banding or clipping of saturated colours. Any colour space other than sRGB really needs 16bit and that's the best reason for using sRGB - it was designed for 8bit images.
I've never experience this but I understand what you mean. Is my monitor likely to be 16-bit (cheapo 17" non-branded (I doubt it))? It isn't calibrated but this is something I'm going to look into now.
If I work in 16-bit, and experience banding, and save a 16-bit TIFF, a printlab wouldn't see the same banding would it?
Like I say, it was just a quick experiment, but it's opened my eyes to how it can affect an image.
pxl8
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I've never experience this but I understand what you mean. Is my monitor likely to be 16-bit (cheapo 17" non-branded (I doubt it))? It isn't calibrated but this is something I'm going to look into now.
If I work in 16-bit, and experience banding, and save a 16-bit TIFF, a printlab wouldn't see the same banding would it?
Like I say, it was just a quick experiment, but it's opened my eyes to how it can affect an image.
You're confusing 16bit total and 16bit per channel.
sRGB 8bits per channel has a total 16.7m colours
Larger colour spaces have room for greater colour saturation and need 16bits per channel to store the extra data.
Most output devices (monitor, printer, etc) are 8bit per channel so the extra data in the 16bit image needs to be squashed down to fit. The two main choices are keep the more saturated colours but at the cost of banding or clip the extra colours to prevent banding.
However not all images actually have colours that use the larger colour space so in most cases it won't be much of a problem - but when you have an image that does use more saturated colours of the larger space unless you can output in 16bit per channel you will lose the data.
As stated above most labs are 8bit and sRGB which is also safe for web, etc. so sticking with that will save a lot of headaches.