Posted: Fri Mar 20, 2009 2:59 pm Post subject: 8 bit vs 16 bit vs 32 bit
Hi, all. I just got CS4 installed and running on my MacBook Pro, and have a couple of questions about bit resolution. I'm shooting with a Canon Mark IIn, all RAW files. I normally do my PP work, then save as JPEG (largest possible setting).
Should I use 8 bit, 16 bit, or 32 bit for this?
And...is there a way to set the bit size as a default setting in Photoshop?
Joined: 24 Sep 2007
Posts: 3515
Location: Haverhill, UK PS Version: Lightroom 5, CS4 & Elements 11 OS: Windows 8.1
Posted: Sat Mar 21, 2009 5:00 pm Post subject:
Hey gymdad,
8 bit is 16.7 million colours, 16 bit is billions of colours, and 32 bit is some amazing amount of numbers that I can't remember the name for lol. Suffice to say, it's trillions and trillions because of the large bit rate. Keep in mind though that printers have trouble printing all the colours of an 8 bit image, while screen output doesn't generally handle any more than 8 bit either. High bit depths are great for editing in, as they enable more smoother colour transitions and less banding etc, but 8 bit is perfect for output 9 times out of 10.
Hope that helps _________________ Matt
3photoshop.com
http://www.3photoshop.com
PS Version: Photoshop 7 to CS4; Elements 3 to 7 OS: Mac OS 10.5; Windows XP
Posted: Sat Mar 21, 2009 5:32 pm Post subject:
8-bit = 16.7 million colors
16-bit = 35.2 trillion colors (35,184,372,088,832)
32-bit = about 79,230,000,000,000,000,000,000,000,000 but I hear it is even more because there are floating point calculations
Generally the idea of a bit is that each has 2 positions, (on/off). As you add bits, you add combinations.
1 bit has 2: on, off
2 bit has 4: on/on, on/off, off/on, off/off
the equation is: 2^e (where e=number of bits)
16-bit is a little different because the 16th bit is not used for color content.
What you should use is a different choice all together:
* 8-bit is what you can use in print and on the web currently.
* 16-bit offers more flexibility and allows you to work with higher bit images that you will have working with RAW files
* 32-bit is currently intended for HDR images
The arguments for 8-bit and 16-bit are easier to make. 8-bit is all you can use and all you can see (except on specialized equipment), so some believe it is best to work in that range. 16-bit retains more of the original information and offers flexibility in rescuing exposures; but you have to convert to 8-bit for use (or something in your process will have to do it for you).
But you say one thing that makes the decision for you: you store in JPEG...and JPEG only uses 8-bits. You can't get more into a JPEG as they are meant to be lean.
I would suggest against using JPEG for storage, however...it is a lossy format and your images degrade as they are encoded upon saving.
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum You cannot attach files in this forum You can download files in this forum
Welcome aboard.
