| Author | Message | ||
     Thomas H Stearns Member Username: Tomstearns Post Number: 10 Registered: 11-2005 |
An expert digital printer opened one of my files in Photoshop and commented that the file was 8-bit color and 16-bit would be much better. This file reads "24bit" in PWPro. None of the current "35m DSLR's" offer 16bit colour--they are 12bit max. Where does the 16bit come from? Does it matter? Can I convert my 8 (or 24) bit PWPro files to 16 bit? | ||
| Kiril Sinkel Member Username: Ksinkel Post Number: 221 Registered: 08-2002 |
There are two standard representations for pixel data -- 8 bit per channel and 16 bit per channel. So to preserve the full output of any device that produces more than 8 bits per channel, you must use the 16 bit format. 12 bits is actually much better than 8. In 8 bits one can represent only 256 distinct brightness levels. In 12 bits one can represent 4096. Kiril | ||
| Kevin Elliott Member Username: Kevgermany Post Number: 336 Registered: 09-2004 |
24bits/pixel is 8 bits in each of the 3 colour channels, i.e. 8x3=24. 48bits/pixel is 16x3=48. Because of the way pcs work, it's not really practical to have a number of pixels/channel between these values. When you convert from the raw file in the DSLR, converting upwards to 16 bits/channel or a 48bit file preserves all the information, whereas the 8 bits/channel sacrifices a lot of fine detail. (8bits has one sixteenth the number of levels that 12 bits has). Does it make a difference - with small amount of manipulation and smallish prints, probably not. With a lot of manipulation and / or bigger prints, yes it does, but it depends a lot on the image type how noticeable it is. PWP can do the conversions Transformation/convert, but you should also be aware that .jpg files are restricted to 8 bits/channel and so you need to use .tiff files to store the greater bit depth. | ||
| den Member Username: Den Post Number: 12 Registered: 03-2006 |
I am going to start an answer thread here but in the future post questions on the PW Support message board not on PW Tips.... Your confusion revolves around the use of the word 'bit' in reference to color depth vs image file depth.... 1) 8-bit tiff or jpeg files have 24 bit color depth 2) 16-bit tiff files have 48 bit color depth Yes, camera raws files have only 12-bit file depth but can either be converted with a raw converted to 1) or 2) above... in the case of 1) data is lost and in the case of 2) no data is lost but the file contains empty data bits that will increase the required disc space for storage Generally, the most conservative approach to camera download image post processing is to convert the raw file to 16-bit tiff (48bit-color) and perform the post-processing workflow... However, adequate images may be obtained from post-processing 8-bit tiffs or jpegs [both having 24-bit color] especially if you have limited disc space, an older processing chip, and low RAM memory... In any case, currently, image files when sent to the printer if not 8-bit (24-bit color) will be converted by the printer driver to 8-bit as there are no available consumer 16-bit capable printers. Hope this helps.... | ||
| Thomas H Stearns Member Username: Tomstearns Post Number: 11 Registered: 11-2005 |
Thanks, guys, for your clarifications. I should have expected a language problem, ie a Photoshop bit is not always a PWProbit. | ||
| Amit Mukherjee New member Username: Amukher Post Number: 7 Registered: 07-2005 |
I am sure that you understand the difference between 8 bit and 16 bit by now. The real question however is whether you really see any difference in the print. A histogram will show you that 16 bit contains more continuous tones than 8 bit. But were you really dissatisfied with your 8 bit pictures in the first place. To use 16 bit, you might need to increase RAM and processor speed and storage can also be an issue. |
