Photographer
Mad Hatter Imagery
Posts: 1669
Buffalo, New York, US
I have 2 images. They are the same dimensions and same dpi. Yet when I try to print them they preview at different sizes at 100% scale. The bit depth is the only difference I can tell from details. One is 32 and the other 48. What else could be going on?
Photographer
G Reese
Posts: 914
Marion, Indiana, US
Would need more info to be sure but it's most likely the bit depth. Wild guess, 15 to 20% difference in print size.
Photographer
Mad Hatter Imagery
Posts: 1669
Buffalo, New York, US
G Reese wrote:
Would need more info to be sure but it's most likely the bit depth. Wild guess, 15 to 20% difference in print size. What decides bit depth? Is there normally a field to alter that number?
Photographer
David Miller
Posts: 173
San Diego, California, US
Mad Hatter Imagery wrote:
What decides bit depth? Is there normally a field to alter that number? As I understand it, the bit depth can be reduced, but not expanded, because it refers to the number of possible colors stored in an image file. A smaller bit depth means that fewer discrete colors can be stored in the file, so reducing the depth will create an image with fewer colors that the original, and in my experience does not change the print size of the image. Since a file containing fewer possible colors is generally not a desired outcome, perhaps resizing the image to produce the printed result you are after is a better way to go.
For the record, I use Paint Shop Pro X9, and not Photoshop, so I am not familiar with other adjustments Photoshop may have to resolve the issue.
Photographer
G Reese
Posts: 914
Marion, Indiana, US
Nor is there reference to it in Paint Shop Pro 20.
Maybe the "experts" here would help out with this issue? :-)
Photographer
The Next Cliche
Posts: 55
Waterloo, Ontario, Canada
Same dimensions - in inches/centimeters or pixels?
Photographer
Mad Hatter Imagery
Posts: 1669
Buffalo, New York, US
David Miller wrote:
As I understand it, the bit depth can be reduced, but not expanded, because it refers to the number of possible colors stored in an image file. A smaller bit depth means that fewer discrete colors can be stored in the file, so reducing the depth will create an image with fewer colors that the original, and in my experience does not change the print size of the image. Since a file containing fewer possible colors is generally not a desired outcome, perhaps resizing the image to produce the printed result you are after is a better way to go.
For the record, I use Paint Shop Pro X9, and not Photoshop, so I am not familiar with other adjustments Photoshop may have to resolve the issue. I use the same, I don't expect to increase image quality by reincreasing bit depth. I just want final files to have same standards.
Photographer
Mad Hatter Imagery
Posts: 1669
Buffalo, New York, US
The Next Cliche wrote:
Same dimensions - in inches/centimeters or pixels? Should be pixels.
Photographer
The Other Place
Posts: 558
Los Angeles, California, US
David Miller wrote:
As I understand it, the bit depth can be reduced, but not expanded, Bit depth can be increased, but color depth will remain the same (unless something artificial is introduced to an image).
Please note that:
BIT DEPTH ≠ COLOR DEPTH
... and that:
COLOR DEPTH = BIT DEPTH x RESOLUTION.
David Miller wrote:
because it refers to the number of possible colors stored in an image file. The number of possible colors in an image file would be its color depth -- not bit depth.
David Miller wrote:
A smaller bit depth means that fewer discrete colors can be stored in the file Not necessarily. Resolution and bit depth are the two main factors of color depth in digital imaging, and one can lower resolution to get more bit depth -- while maintaining the same amount of color depth. The reverse should be true, but I have never seen any examples.
Photographer
Shadow Dancer
Posts: 9782
Bellingham, Washington, US
Not sure why this is so complicated?
I used to be a printer. Go into Photoshop and resize the images so they are what you need, then print them.
Everything else is quibbling. The limitations on quality are almost entirely printer based so the prints shouldn't look much different at all.
Easy, on to the next.
Photographer
David Miller
Posts: 173
San Diego, California, US
David Miller wrote:
As I understand it, the bit depth can be reduced, but not expanded, The Other Place wrote:
Bit depth can be increased, but color depth will remain the same (unless something artificial is introduced to an image).
Please note that:
BIT DEPTH ≠ COLOR DEPTH
... and that:
COLOR DEPTH = BIT DEPTH x RESOLUTION. Ah, I see, and thanks for shedding light on the issue.
Photographer
Robert Lynch
Posts: 2550
Bowie, Maryland, US
David Miller wrote:
David Miller wrote:
As I understand it, the bit depth can be reduced, but not expanded, Ah, I see, and thanks for shedding light on the issue. Resolution has absolutely no bearing on color depth. Where do people get these ideas?
https://en.wikipedia.org/wiki/Color_depth
Photographer
Robert Lynch
Posts: 2550
Bowie, Maryland, US
David Miller wrote:
As I understand it, the bit depth can be reduced, but not expanded, The Other Place wrote:
Bit depth can be increased, but color depth will remain the same (unless something artificial is introduced to an image).
Please note that:
BIT DEPTH ≠ COLOR DEPTH
... and that:
COLOR DEPTH = BIT DEPTH x RESOLUTION. David Miller wrote:
Ah, I see, and thanks for shedding light on the issue. Resolution has absolutely no bearing on color depth. Where do people get these ideas?
https://en.wikipedia.org/wiki/Color_depth
Photographer
Studio NSFW
Posts: 783
Pacifica, California, US
The question is about why they are previewing at different size, if I understand the original poster. Print size would be different from preview size.
I have no eye deer if this is right but it strikes me that a 16 bit color depth pixel contains twice as much info as an 8 bit pixel. So, it’s a “bigger” pixel. And maybe that informs how Photoshop is previewing a given image….bigger pixels?
16 bit color depth in an image file DOES create a larger file from a storage capacity standpoint than an 8….simply because there is more information. You are up in 48 bit color depth so it’s a lot of info
When setting up the print job, is Photoshop set to display measurement in Pixels? If so, switch it over to inches or centimeters for print size and *perhaps* the behavior will change. I dunno, I never have run into this personally….the only time I get an unexpected image size when printing is when I (all too often) forget to change my paper size and burn a 16x20 sheet with an 8x10 image…which happens often enough that I worked out how to print 3 more 8x10 “Bonus prints” when I do that…
Photographer
The Other Place
Posts: 558
Los Angeles, California, US
Robert Lynch wrote:
Resolution has absolutely no bearing on color depth. Where do people get these ideas?
https://en.wikipedia.org/wiki/Color_depth Resolution is absolutely a factor in color depth -- equal to bit depth (in digital imaging).
This fact allows one to swap resolution for bit depth.
Additionally, the fact that resolution affects color depth is clearly demonstrated with screen/halftone printing. Halftone printing is just black dots on a white background -- which is "one bit" imaging. How can so many different shades appear in a one bit imaging system? Given just black dots and white, the image should not have any shades in between black and white, if bit depth is the only determining factor of color depth. Also, why does the number of shades increase when finer screens (higher resolutions) are used? The same questions apply to color screen printing.
Furthermore, the reason why 4:4:4 digital images have more color depth than 4:2:0 digital images is precisely because 4:4:4 is a higher color resolution than 4:2:0.
Also, color depth can exist without any bit depth at all -- consider the color depth of analog (emulsion) imaging.
It is a common misconception that bit depth is color depth in digital imaging -- it's actually one of two main factors of color depth. Wikipedia is just incorrect (imagine that).
Photographer
Robert Lynch
Posts: 2550
Bowie, Maryland, US
The Other Place wrote:
Resolution is absolutely a factor in color depth -- equal to bit depth (in digital imaging).
This fact allows one to swap resolution for bit depth.
Additionally, the fact that resolution affects color depth is clearly demonstrated with screen/halftone printing. Halftone printing is just black dots on a white background -- which is "one bit" imaging. How can so many different shades appear in a one bit imaging system? Given just black dots and white, the image should not have any shades in between black and white, if bit depth is the only determining factor of color depth. Also, why does the number of shades increase when finer screens (higher resolutions) are used? The same questions apply to color screen printing.
Furthermore, the reason why 4:4:4 digital images have more color depth than 4:2:0 digital images is precisely because 4:4:4 is a higher color resolution than 4:2:0.
Also, color depth can exist without any bit depth at all -- consider the color depth of analog (emulsion) imaging.
It is a common misconception that bit depth is color depth in digital imaging -- it's actually one of two main factors of color depth. Wikipedia is just incorrect (imagine that). Wikipedia was just the easiest to reference. It’s the same everywhere else.
There is a terminology and perspective problem here. You are talking about dithering. The color depth of a digital image is determined by the number of bits of color information per pixel, not its resolution (the number of pixels). How well those colors are reproduced is determined in part by how small the dots of a limited number of colors are when used to create the illusion of more colors through dithering. The dot size of the output device is a physical property of the device. It has no connection to the resolution of the image being reproduced.
Photographer
The Other Place
Posts: 558
Los Angeles, California, US
Robert Lynch wrote:
You are talking about dithering. No, I am not.
There's no dithering involved in any of the examples that I mentioned. Where's the dithering in the practice of swapping resolution for bit depth while maintaining color depth? Where's the dithering in analog halftone printing? ... and in chroma subsampling? ... and in continuous tone emulsion?
Even if dithering was involved in one or more of the processes that I mentioned, resolution is obviously still a factor of color depth in those situations.
Robert Lynch wrote:
The color depth of a digital image is determined by the number of bits of color information per pixel, not its resolution (the number of pixels). No. Resolution is a factor of color depth, equal to bit depth. I have given four examples.
Robert Lynch wrote:
How well those colors are reproduced is determined in part by how small the dots of a limited number of colors are when used to create the illusion of more colors through dithering. What dithering?
Robert Lynch wrote:
The dot size of the output device is a physical property of the device. It has no connection to the resolution of the image being reproduced. Perhaps (if the resolution of the output device is the same as the source image), but how is that relevant to the fact that resolution and bit depth determine color depth?
Photographer
Frozen Instant Imagery
Posts: 4152
Melbourne, Victoria, Australia
Here’s what I know.
My printer is an Epson P900. It can print teeny tiny dots at 5760dpi using a fixed set of 9 different colours of ink (3 shades of black/grey, 2 each of cyan and magenta, 1 yellow and 1 violet).
I send 8 bit RGB images to the printer to be printed at 300dpi (or thereabouts).
In between the 300dpi at millions of colours and the 5760dpi at 9 colours, I am pretty confident there is some dithering going on. Or maybe it’s the sacrifice of expensive ink to Chromos the god of colour? Or just magic? Yeah, I’ll settle for magic.
Clothing Designer
veypurr
Posts: 464
Albuquerque, New Mexico, US
All print sizes are equal but some are more equal than others.
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