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8 Bits, 16 Bits, and higher dpi resolutions
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Hi everyone,
I’m hoping you can help me with somethings that I’m sure are basic knowledge once you know it!
I’m confused about what exactly the 8bit and 16bits options in Photoshop are.
My friend is a graphic designer and he says it makes a difference to the image but I don’t know what that difference is nor do I know what’s best the best choice for photography.
He said that in order for an image to be 16bits that it needs to be photographed at 16bits – is that right?
I have a Canon 400D and never noticed that as a ‘bits’ setting on it.Also, when I open an image in Photoshop it’s 72dpi resolution by default. I know that if I increase the dpi then the physical image size gets smaller.
A friend of mine said though that you can set your camera to take pictures at a higher resolution? Again, this is never a setting I’ve been able to find.
I’d love to be able to set my camera to 300dpi so that my pictures come out full size as normal (ie. the same size I get by taking then currently) but with a 300dpi so that I don’t loose any size when I print them and I wouldn’t have to change the dpi to optimise it for print and thus make my image smaller.
Is it possible to take photos at 300dpi (or any other larger dpi) whilst keeping the image size big?Thanks for all your help guys and gals.
My mind’s a little boggled by all this but I feel it’s some essentials I need to know.
OK, I’m going to be really lazy here and point you somewhere else :wink:
For your question on 8-bit -v- 16-bit, have a look at this tutorial – http://www.cambridgeincolour.com/tutorials/bit-depth.htm Hopefully that will give you an understanding of the benefits (and importance) of 16-bit images. Anyone that shoots JPEG only will be working with 8-bit images. In order to enjoy the benefits of 16-bit you need to be shooting RAW and then convert to a 16-bit image.
The second part of your question is addressed in this tutorial – http://www.cambridgeincolour.com/tutorials/digital-camera-pixel.htm The easiest way to think of a pixel is just like another unit of measure like an inch, a centimetre, a mile or a kilometre. While this isn’t technically correct, I feel it does help to get the concept across. Each of these is a different length and we understand that because we are so used to working with these units. An image that is 800 pixels wide will always be 800 pixels wide regardless of whether the resolution is set to 300dpi or 72dpi, so you can forget about this resolution figure UNTIL IT’S TIME TO PRINT. This is an important concept – if you print your 800 pixel wide image at 72 dpi (dots per inch) then it’s going to be 800/72 inches wide (just over 11 inches). If you print the same 800 pixel image at 300 dpi, then it’s going to be 800/300 inches wide (2.67″).
Thanks Thorsten
those articles explain quite a lot.So just so I’m clear – would I be correct in saying that when you shoot and save as JPEG that the image you are saving will be 8bit and 72dpi?
If I want an image thats 16bit and a higher dpi I need to shoot in RAW and then choose those settings when I’m processing the RAW image yes? There are no actual ‘settings’ on the camera for this. They’re set in post yes?Thanks again.
pihjin wrote:
So just so I’m clear – would I be correct in saying that when you shoot and save as JPEG that the image you are saving will be 8bit and 72dpi?
Basically yes. The JPEG file format doesn’t support 16-bit images, only 8-bit. This, for me at least, is one of the principle reasons I don’t shoot JPEG. Note, however, that a RAW file isn’t normally a full 16-bit image either but usually 12-bit or, more recently, 14-bit. As for the camera saving the images as 72dpi or 300dpi, it doesn’t matter – at the end of the day, the camera is saving an image that is x-number of pixels across and y-number of pixels high. It’s only when you want to convert your image to a print that you really need to concern yourself with dpi.
Was just about to add a topic on this – thanks for the answers!
Was onto a stock agency that kept telling me that my camera needed to be 300dpi – thought it very strange as was sure that this was only of a concern at printing.. delighted that you explained it so well above..This post has explained a hell of a lot to me, DPI used to always confuse me.
Damn I saved so many of my images in jpeg, :( ….guess not anymore :)
I rarely print and when I do it’s at a kiosk so I really dopn’t have to worry for this.Evan
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