[photog]

Hi Class A you ask "Are you sure about this?". In relationship to image processing a 16 bit image has a greater density of information. When exposure / brightness (gamma) / contrast and related adjustments is increased the image is much less inclined to become banded. I histogram view the graph will be seen as having a combed appearance.
The range of colours seen is defines as the gamut. sRGB is the most limited but is still better than the average LCD monitor. Professional and really serious amateurs spend serious dallars / euros in monitors that can approach and even exceed the much wider Adobe RBG 1998 colour space. Mosr run of the mill inkjet printers can only achieve sRGB as well. Lightroom uses a higher processes in a much larger colour space and then exports in the colour space that you choose.
I also use LR2 because it can display, process (develop) RAW files DNG / PEF or whatever your DSLR supports. LR2 works in ProPhoto a very wide space, and by default frocesses in 16 BIT.
So why process in a colour space you cannot print? Simply because colours / brightness valuse that blow out (clip) in 8 bit can be processed an adjusted. They can then be exported and printed.
If you printed directly from LR2 they are rerender directly to the printer. If you are using a good photo printer LR2 will be able to render the image printed without needing to produce an image in the colour space the printer can use. In the print options you choose "perceptual". This will deliver aan image more closely resembling the true colour.
I know that purists will say that it is not posible to print from a raw file. LR2 may well make a "temp" file but it will also delete it when finished. You will never have to store or manage anything except the original RAW files (negatives)
Ane Lightroon 2.4 is totally non-lossy. You can go back to scratch at any time. And the history feature is magic.
Ron McDermot

[photog]

Hi Class A. I googled the question of 8 or 16 bit - Picasa. No where did I find and indication that it uses 16 bit.
Ron McDermott

[ytterbium]

Most correct approach would be NOT USING any bit depth INTEGER type VARIABLES AND limited COLOUR SPACES during processing. So even if you boost brightness or increase contrast milion times, next operation doing exact oposite would yield the same image you began with.

With integer variables you can easy saturate them or compress dynamic range in to very few bits (practically doing something like the posterize operation). So you must think your processing steps very carefully so that you preserve maximum quality to the end.

Using integer variables is LOSSY in a way. So it is best that conversion to it is done only when writing to file or outputing to device (like printer).
In practice it would be VERY slow. Best solution would be working with integer calculated previews and having high precision final render.

Talking about Picasa, i belive it does some fully automatic RAW rendering and then hands it to standart Picasa 8-bit editing tools used for all images.

[photog]

8 or 16 bit does not refer to the number of colours rendered. Wide gamut or colour space can be achieved with sRGB or Adpbe RGB etc.

[ytterbium]

Just wanted to tell that Picasa and UFRaw ended up being really helpfull in such situations, where Pentax colour scheme could not manage to preserve detail.
I guess i should get a larger memory card and start shooting exclusively RAW, since it adds much more confidence and eases the shooting process (don't have to think about WB indoors with flash and multiple lights, impossible to miss a shot due to wrong jpeg settings or fiddling with them instead of just shooting).
Those JPEG got really messed up while uploading, but still you can see the colour rendering (InCamera, UFRaw - overdone a bit, Picasa).

[photog]

I have processed a 16 bit raw image of a deep red rose. No colour is clipped. I rerendered it as 8 bit jpg. Clipping of reds is severe. It is clear viewing the originals the value of 16 bit colour. Camera was the K10
If the images fail to load I will try again singly.
Ron McDermott
BTW they need to be viewed by 16 bit colour program.

[ytterbium]

I'm sorry, but after reading several timaes, I could not understand what your'e saying.
16bit viewer? Most LCD screens have 6 bit colour space anyway. CRT have 8bit.

My topic was basically about rendering 14bit->8bit without clipping.

[Class A]

Sorry for the late replies. I was away from the forum for a while.

Hi Class A you ask "Are you sure about this?".

Yes, but my question only targeted your knowledge about Picasa. I know about the relationship between number of bits and colour depths.

I googled the question of 8 or 16 bit - Picasa. No where did I find and indication that it uses 16 bit.

But I guess you didn't find an indication that it uses 8-bit for RAW processing either?

Talking about Picasa, i belive it does some fully automatic RAW rendering and then hands it to standart Picasa 8-bit editing tools used for all images.

That may be true but what makes you believe it is that way?

8 or 16 bit does not refer to the number of colours rendered.

That's not true. The number of bits correspond to the number of colours that can be displayed. A simple example is a 1-bit format. It can only support two colours, say black and white or some other combination like orange and blue. You may choose any two colours because low-bit presentations like this typically use a palette which is indexed and may contain arbitrary colours.

Just wanted to tell that Picasa and UFRaw ended up being really helpfull in such situations, where Pentax colour scheme could not manage to preserve detail.

There is no "Pentax colour scheme" as such. Pentax cameras support sRGB, adobeRGB and RAW (PEF, DNG) which (with the exception of PEF) are all Pentax independent standards.
The difference you are seeing does not come from a particular choice of a colour scheme but from the parameters you chose when converting the RAW data into an 8-bit format. You can get that oversaturation with any format and tool if you set the parameters accordingly.

To avoid oversaturation of flower shots, set your camera to "natural" and perhaps reduce "saturation" (and potentially "contrast") a notch. Granted, RAW shooting will give you a bit more headroom in postprocessing but usually it is possible to survive with JPEGs and even if you shoot RAW, the camera settings will often be respected in the conversion, giving you a better starting point to adjust from.