New camera settings ?

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Re: New camera settings ?

Postby Codebreaker » Sat Dec 13, 2008 4:55 am

Jim, is absolutely right. The three basic rules of photography....

1. f8
2. 1/125s
3. Be there


#3 being the most important.

Have fun

Colin

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Re: New camera settings ?

Postby im42n8 » Sat Dec 13, 2008 6:27 am

If one thinks that all color spaces have the same number of colors then someone is and has been drinking way too much hoooey! :shock:

If all color spaces were the same then we wouldn't have CMYK, L.A.B., sRGB, Adobe RGB, ProPhoto, etc.!!!! These are all representations of color within RGB. And they're ALL different. LAB may have the widest representation while sRGB may have the least number of colors represented. Each has its uses, advantages, disadvantages.

A representation of a color doesn't necessarily mean that it's correct representation of the actual color... it might just mean that it's been mapped to the current color space which is different than the original. Sometimes that mapping is a bit off too (tho as good as it can get). For instance, there are a number of problems when moving from sRGB to CMYK (because the colors don't quite match). Just ask any Printer (the book/magazine/brochures type!) who how must convert sRGB images into CMYK for publishing! It can be a nightmare!

When we move between color spaces a mapping occurs between those spaces. A color gamut is just that: the range of colors available to that color space. If you map a larger gamut to a smaller one, you lose the range of colors existing outside the spectrum of the smaller gamut. You don't get them back if you convert back to the larger gamut (when you're editing a photo, for instance). While the original image had the full color spectrum, the converted image now has a spectrum limited by the existing gamut being used. So, when you're viewing an image that was taken using the Adobe RGB color space, the available colors are mapped onto the screen to the sRGB device (the monitor). You only see the colors available to the sRGB color space.

You might want to reference the following: http://www.naturephotographers.net/arti ... 203-1.html
There are quite a few references out there to address the issues of the different color spaces and their respective gamuts. Some more authoritative than others. They can help you understand some of the issues facing the DLSR users of today!

Dale

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Re: New camera settings ?

Postby Codebreaker » Sat Dec 13, 2008 7:50 am

Dale.....

Ok, so you are missing the point. :) I've studied Colour Management for some years now and written papers on the subject. Of course you can only take my word that I do know what I'm talking about :wink:

Colour spaces have the same number of colours but different ranges. JPEG images can only reproduce 16.7M different colours but the range of colours may well be different depending on the colour space. Prophoto, AdobeRGB have a much wider range of colours than sRGB but the have the exact same number of colours in the digital image....same number but different range.

RAW images can deliver more colours because they may use 12 or 14 bits per colour channel but if you convert these to even a 16bit colour mode there will still be a finite number of colours available irrespective of colour space.

Yes one range will have colours the other doesn't but it doesn't actually have more discrete colours.

While its technically possible to divide a colour space into an infinite number of individual colours - (well limited by the wavelengths), digital images have a finite number due to the number of bits used to represent those colours. This doesn't change between colours spaces - only the meaning of the colour represented by the number changes.

The issue is not that different colour spaces may be able to reproduce colours that others can't, but that each space can only produce the same number of discrete colours....16.7M for 8bit images

Here's an analogy for you. Take two pieces of straight wood of different lengths. Make marks at 10 equal points along each piece. Lay the two pieces on some paper on which is printed the spectrum of visible light. Make the two pieces start at the same point.

One piece will cover a wider range of the spectrum than the other. Each mark is the only available colour that can be represented by a number. The 5th mark on each is at a different colour. Its half way along the range of both but represents a different colour. Each piece of wood has the same number of marks but each mark is a different colour except the starting point in this example.

If you want a definitive book on the subject read Bruce Frasers - Real World Colour Management.

Colin

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Re: New camera settings ?

Postby im42n8 » Sat Dec 13, 2008 9:36 am

Thanx Colin,

You're right! It just took a bit more time to get my noggin around the colors vs gamut issue.

So, I think he should shoot in Adobe RGB if he's going to primarily print his images. If they're all going to end up on the web or on his display, then sRGB is his best bet (or, SHOOT in Adobe RGB ... then, for those images that will be destined for the web/monitor display, convert them to sRGB to avoid the washed-out appearance of an Adobe RGB image that's displayed on an sRGB display).

Dale

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Re: New camera settings ?

Postby Codebreaker » Sat Dec 13, 2008 10:04 am

No problem Dale....its a very tricky subject which is why I often say start with sRGB because it might produce less surprises. Its the lowest common denominator, so to speak.

As for choosing a setting of AdobeRGB just because of printing depends on the printer and is it capable of covering any of the range. Then comes the issue of who does the Colour Management. Photoshop does this very well but some printer drivers don't allow any control - possibly even assuming the image data they are being sent is in the sRGB colour space.

Then there's Rendering Intent to consider and so on. I have some basic information based around Photoshop Elements on my web site. Take a look if you wish....

http://homepage.ntlworld.com/colin_w/co ... oblems.htm

Have a great christmas...

Colin

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Re: New camera settings ?

Postby briancbb » Sat Dec 13, 2008 3:42 pm

Colin

That last but one post of yours is a great explaination. Thanks
Briancbb (Brian, Clown by birth)
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Re: New camera settings ?

Postby Codebreaker » Tue Dec 23, 2008 2:24 am

Brian....

I'm glad it helped. It under lines two of the basic issues of colour management....

1. With devices having different gamuts and the same set of numbers to play with - who decides what number means what colour.
2. When moving images from one device to another e.g camera to display or camera to printer - how are the colour numbers translated.

Its always a compromise.

Colin

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