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Capocheny
25-Feb-2007, 20:04
Greetings,

Just a quick question for those LF photographers who shoot film, have them digitally scanned and printed at a pro-lab...

1. What bit size do you have the lab print in? For example, I took some discs in to the lab and they said they don't print in 16 bit sizes.

2. What dpi are you using most commonly for a maximum image size of 16x20? In the past, I've used 300 dpi. However, is there any advantage to using something higher?

3. Lastly, what format (Tiff, jpeg, etc) works best for your printing needs? Any suggestions?

FWIW, I'm shooting 4x5, 5x7, and 8x10... predominantly HP5+ and FP4+. The lab also soups my films. :)

Thanks in advance for any suggestions and comments.

Cheers

Brian Ellis
25-Feb-2007, 20:50
1. It's my understanding that most (not all) printers print in 8 bit no matter what you send to them, which is probably why your lab said what they did. But apart from that, I don't think there's any advantage to sending a 16 bit file to the printer - 16 bits is important for editing but I'd be surprised if you noticed any difference between sending an 8 bit file or a 16 bit file to the printer even if the printer was capable of printing in 16 bits. I've seen heated arguments about this point but generally it was one person saying he or she saw a difference vs 10 saying there was no difference.

2. 300 bits is a common number. I'd suggest trying different size prints at differnt dpi and see what you get. When I attended his workshop George deWolfe said that tests run by a consortium consisting of him and a bunch of other notables showed that 420 bits or something like that was the optimum number but I've never aimed for that number myself.

3. I don't know that the file format matters solely for printing. But I save all files as tifs so that's what I send to the printer.

There are people here who know more than I do about all this stuff, I'm still learning. If one of them contradicts anything I've said here ignore what I've said and listen to what they say.

PViapiano
25-Feb-2007, 21:15
Each digital printer and specific models, be it Noritsu or Frontier or whatever, have a specific dpi that is optimal for output. Ask your lab for all the specifics...

If you order online from Adorama, WHCC or elsewhere, there is usually a web page that lists the exact format and resolution that they need to optimally print your image, or you can email them for the info...

So, yes...8 bit, usually 300 (but check to make sure, some printers like to see odd numbers), and TIF or JPG are usually the standard.

roteague
25-Feb-2007, 21:33
8 bit at 300 dpi should do you just fine. Most people can't distinguish more than 8 bit color anyway. Always TIFF, never jpg.

Capocheny
26-Feb-2007, 00:59
Hi Brian, PV, Robert,

Thanks for your input...

How about scanning B&W negs... do you scan yours in 8 or 16 bit? My understanding is that you pull more detail/information off the neg with 16 bit. But, the file sizes are huge relative to scanning them in 8 bit.

Cheers

Bruce Watson
26-Feb-2007, 07:29
1. What bit size do you have the lab print in? For example, I took some discs in to the lab and they said they don't print in 16 bit sizes.

2. What dpi are you using most commonly for a maximum image size of 16x20? In the past, I've used 300 dpi. However, is there any advantage to using something higher?

3. Lastly, what format (Tiff, jpeg, etc) works best for your printing needs? Any suggestions?

All these depend on what machine your lab uses as a printer.

1) Most printer drivers want 8 bit files. Most of the drivers will compress 16 bit files on the fly to 8 bit. Some will not. Newer machines like the new Canon wide format printers have 16 bit drivers available. Ask your lab for specifics on what they want from you. If they don't know, find a lab that does.

2) Again, optimum file resolution depends on the machine doing the printing. Large Epson inkjet printers like 360ppi. Lightjet machines like 304.8ppi (that's 120ppcm). Again, ask your lab what their machine wants.

3) Once again, it depends on your lab. Ask them what file format they want your file to be in.

While you are asking the lab questions, ask them for an ICC profile so you can soft proof on your home PC. Ask them what color space they want the file to be in. Most will want Adobe RGB 1998, some can handle bigger spaces like ProPhoto RGB. I would worry about the ones that want sRGB because it is too restrictive for my tastes.

Then, ask them if there's anything else they want from you that you haven't asked about yet. All this in the name of proper communication between the two of you so that you both get what you want.

Bruce Watson
26-Feb-2007, 07:35
How about scanning B&W negs... do you scan yours in 8 or 16 bit?

I scan B&W negatives only in 16 bit. Yes the file size is exactly twice as big vs. 8 bit files. Put another way, the file size is 1/3 that of 16 bit color scans. As the Borg would say, size is irrelevant.

Every image I've scanned has needed some editing. Some small, most somewhat more. It's the ones that have more than "small" editing that need the 16 bits. Even medium changes in 8 bits can give you posterization. And with B&W you don't have color to hide behind --- everything is visible, including the smallest amount of posterization.

bob carnie
26-Feb-2007, 07:41
Our Lambda prints at 200ppi and at 400ppi , it is a 8bit printer.
As others have noted image editing in 16bit is what most do, and we accept in either 16 or 8 bit.
There is a noticable difference at 400ppi. Before we purchased our own machine we rented time on another labs machine which ran at 200ppi, when we landed our own Lambda we switched to 400ppi . It takes twice the time to expose but we see the difference.
It becomes problematic when clients capture with small files and want to push the print size up and up. *mostly posterization like* abberations in the highlight region.

PViapiano
26-Feb-2007, 09:46
I scan and edit in 16 bit and knock it down to 8 bit for printing at home or at a lab.

Marko
26-Feb-2007, 10:10
There is a difference between 16-bit grayscale and 16-bit RGB. They are both 16-bit per channel, but the difference is that grayscale has only one channel and RGB has three. The amount of information is not tripple, however, but exponential, since 16-bits equal to 2^16 = 65,536 and the amount of information in the 3-channel RGB file is actually 65,536^3 (to the power of 3), not 65,536x3. That's billions of shades.

Therefore, even if you scan and process a b&w image, you have that much more information to work with (and can afford to loose during editing) if you acquire and edit in 16-bit RGB until the very end, when you convert to 8-bit RGB for printing.

To make this last bit clear, it is more beneficial to keep the b&w file in RGB for printing as well, because the same math applies. Instead of 2^8 = 256 shades of gray in a grayscale 8-bit file, you end up with (2^8)^3 = 256^3 = approx. 16 million shades of gray for the printer to render.

John Berry
26-Feb-2007, 10:53
I agree with Marko. In RGB you can put a tone curve on a B&W print.

Michael Mutmansky
26-Feb-2007, 12:17
There is a difference between 16-bit grayscale and 16-bit RGB. They are both 16-bit per channel, but the difference is that grayscale has only one channel and RGB has three. The amount of information is not tripple, however, but exponential, since 16-bits equal to 2^16 = 65,536 and the amount of information in the 3-channel RGB file is actually 65,536^3 (to the power of 3), not 65,536x3. That's billions of shades.


Actually, the information is triple. The number of potential colors is much greater than triple, but the information is triple.

However, for B&W, your numerical rationalization is not correct. The increase in meaningful information held in a RGB grayscale image is only about 1.5 bits greater than a comparable grayscale file.


Therefore, even if you scan and process a b&w image, you have that much more information to work with (and can afford to loose during editing) if you acquire and edit in 16-bit RGB until the very end, when you convert to 8-bit RGB for printing.


This is again not entirely true. You have slightly more meaningful grayscale information in an RGB, and for the most part it equates to more dithering in the file, but since there is a huge amount of overage when working at the 16 bit level, I seriously doubt it makes any beneficial difference in the final print.

I do think this would be a very good approach to get a higher bit depth if you had 8 bit files to work with, but at 16 bits, I am doubtful it will have any benefit.


To make this last bit clear, it is more beneficial to keep the b&w file in RGB for printing as well, because the same math applies. Instead of 2^8 = 256 shades of gray in a grayscale 8-bit file, you end up with (2^8)^3 = 256^3 = approx. 16 million shades of gray for the printer to render.

This again, is not correct. Think of it this way. You're saying that you get more information in a grayscale image out of 3 channels of an 8 bit file than you will get out of a single 16 bit grayscale file.

You can't think of a B&W image as unique colors, you have to think of it in terms of unique levels. In this context, a single channel 8 bit image will have 256 levels possible. A 9 bit image will have 512 levels, possible. That will coincide exactly to that number of possible levels from a file that has two channels and are 8 bit. So a three channel B&W 8 bit image will have essentially 1.5 more bit depth than an 8 bit file.


---Michael

Marko
26-Feb-2007, 13:31
Actually, the information is triple. The number of potential colors is much greater than triple, but the information is triple.

However, for B&W, your numerical rationalization is not correct. The increase in meaningful information held in a RGB grayscale image is only about 1.5 bits greater than a comparable grayscale file.



This again, is not correct. Think of it this way. You're saying that you get more information in a grayscale image out of 3 channels of an 8 bit file than you will get out of a single 16 bit grayscale file.

You can't think of a B&W image as unique colors, you have to think of it in terms of unique levels. In this context, a single channel 8 bit image will have 256 levels possible. A 9 bit image will have 512 levels, possible. That will coincide exactly to that number of possible levels from a file that has two channels and are 8 bit. So a three channel B&W 8 bit image will have essentially 1.5 more bit depth than an 8 bit file.

Actually, this is not correct either.

One bit is the the most basic, discrete piece of information, therefore, any amount of information can only be a full multiple of one bit. There is simply no such thing as "1.5 times the bit depth" or "1.5 bits greater", as it makes no sense.

Yes, a file with a single 16-bit channel carries much smaller number of discrete pieces of information - bits - than a file with three 8-bit channels. It's a matter of simple math - the former is a 16-bith file, while the latter is a 24-bit file. The information is cumulative, not additive, so a file containing one 9-bit channel from your example will indeed contain 512 discrete pieces of informaton (2^9), but the file with 2 8-bit channels carries the same amount of information as if it had a single 16-bit channel - (2^8)^2 = 2^16.

There is also no such thing as more or less "meaningful" information. Information on this level is binary, it either IS or it IS NOT.

Michael Mutmansky
26-Feb-2007, 14:03
What I was saying is that using three channels is effectively like using a file with a bit depth 1.5 higher than not having three channels. While a bit is the least increment in a single channel, as soon as you have three channels, you effectively can produce partial bits of information when compared to a single channel file, so my statement is correct.

You are misunderstanding meaningful differences in a file with raw data permutations. When you equate all the possible color combinations in a RGB file with the meaningful information in a grayscale file.

What do I mean by this? Several things. First, if you scan a B&W negative in color and invert it to make a positive, you will have a color image of a black and white source, so the image will probably look more or less B&W.

Take a particular level in that image (lets use 8 bit for the example). Let's take level 128. If you look at a pixel that has a value of 128 (luminance or in a converted grayscale file), you might see a RGB or something like 125,128,131, or so. The three channels will not be permitted to deviate too much from the neutral (nominal) value of 128. So even though you have the potential for a large variety of RGB combinations that equate to a value of 128, there are really only a limited number that will actually occur due to the neutrality of the source negative and the way the the source is mapped to individual RGB values during the scanning.

In other words, if you have a composite value of 128, it is not going to be possible to have a B of 0, and R of 255 and a G of 128, because the neutrality of the negative won't have that kind of deviation happening within it.

The other issue has to do with the compression of all the colors in a color file into levels in a grayscale file. Even if you had the ability to get a scan that had the kinds of variations I mention above, the color engines effectively make many of the possible
color permutations in a color file numerically equivalent in terms of luminance or K values. So while it's possible to have a RGB of 127,128,129, and while this is a different color than another like 129,128,127, the converted grayscale levels of these two numbers could be identical within the bit depth of the file. There are many such permutations that are rendered nemerically equivalent in grayscale.

In other words, while there is a color difference in the file, there is no meaningful levels difference between these two numbers. That's what I mean by meaningful information differences.

(Note that I am not equating these values, I pulled them out of the air as examples.)


---Michael

Marko
26-Feb-2007, 14:27
OK, I see what you mean now and it does make sense.

What I have in mind talking about bits of information is the actual amount of data loss in processing as well as in the translation process during printing. In other words, even though some, or even a good part of it may be redundant, it still provides a much bigger pool to lose - and keep - data from, so that the actual amount of "keeper" data we end up with remains as close to the maximum possible to have in a final 8-bit file.

Michael Mutmansky
26-Feb-2007, 14:35
Marko,

You're absolutely right, and I think that for 8 bit scans or files, that approach is going to go a considerable way toward knocking out the posterization problems that can be experienced. Its a great approach for a person with an old drum scanner, for example.

For high bit depth images, I think there is enough overhead in the images toe avoid having to go to these kinds of heroic measures.

That said, printing color images of B&W files when there is a particular toning that is desired is a very effective approach for some people. However, the file does not have to be RGB throughout for this approach if it is a high bit depth file. Probably can't hurt, though. It simply means working with larger image files.


---Michael

Ron Marshall
26-Feb-2007, 14:42
I scan and manipulate in PS in 16-bit, then convert to 8-bit before sending to the printer.

Capocheny
26-Feb-2007, 22:17
Hi all,

Great advice guys... thanks for all the terrific information. It's much appreciated.

Bruce,

I'll get ahold of the lab and make the necessary inquiries. :)

Again, thanks for all the great advice.

Cheers

Dominique Labrosse
26-Feb-2007, 23:22
Capocheny,

In terms of B&W it breaks down like this...

8 bit B&W has 256 levels of grey (including black and white) which is about what the human eye and brain can work out. 16 bit B&W has a lot more than that (were talking tens of thousands here).

If you plan on printing a scan without manipulating the file then there is no reason to go 16 bit. If however you want to move tonal values around in Photoshop before you print it is better to have a 16 bit scan done. This way you have less of a risk of posterization.

Once you are happy with how your 16 bit file looks then convert it down to 8-bit and save a version to send to the lab.

By the way. Who is scanning and printing your work these days?

Regards,
DL

Capocheny
26-Feb-2007, 23:39
Capocheny,

In terms of B&W it breaks down like this...

8 bit B&W has 256 levels of grey (including black and white) which is about what the human eye and brain can work out. 16 bit B&W has a lot more than that (were talking tens of thousands here).

If you plan on printing a scan without manipulating the file then there is no reason to go 16 bit. If however you want to move tonal values around in Photoshop before you print it is better to have a 16 bit scan done. This way you have less of a risk of posterization.

Once you are happy with how your 16 bit file looks then convert it down to 8-bit and save a version to send to the lab.

By the way. Who is scanning and printing your work these days?

Regards,
DL

Hi Dominique,

Thanks for the info...

One of the guys from last years workshop is scanning some of my negs until I pick up my own V750, which will be sooner than later.

G. King Photo is printing my stuff these days. I really need to get into doing my own printing and contact printing though. Soon! :)

Cheers

Gene McCluney
27-Feb-2007, 01:23
If you are going to get inexpensive proof prints at a one-hour lab such as you might find at Wal-Mart or Walgreens, then you need to give them 8 bit jpg's. They cannot read tif's. ideally you should size your jpgs to the print size you wish in advance. this helps to guarantee that you will get what you want. I always scan at the highest resolution of my scanner in 16bit, either greyscale or RGB, then I make corrections and save as 8 bit tif's. If I want cheap prints, I then convert to jpg, but archive my images in tif format. I have written an action in Photoshop to do the conversion in bulk, resize to 4x6, save as jpg in another folder. The original file is not touched.

Gene McCluney
27-Feb-2007, 01:25
I agree with Marko. In RGB you can put a tone curve on a B&W print.

I am not sure what you are saying here. You can adjust the curves on an greyscale file also. Do you mean a "tint" such as making your images look sepia toned?

Michael Mutmansky
27-Feb-2007, 08:02
Capocheny,

In terms of B&W it breaks down like this...

8 bit B&W has 256 levels of grey (including black and white) which is about what the human eye and brain can work out. 16 bit B&W has a lot more than that (were talking tens of thousands here).

If you plan on printing a scan without manipulating the file then there is no reason to go 16 bit. If however you want to move tonal values around in Photoshop before you print it is better to have a 16 bit scan done. This way you have less of a risk of posterization.

Once you are happy with how your 16 bit file looks then convert it down to 8-bit and save a version to send to the lab.

By the way. Who is scanning and printing your work these days?

Regards,
DL


Dominique,

Unfortunately, this doesn't quite work out as well as it could ideally. I have never seen an 8 bit image file that has had anywhere near 256 levels of gray in them. Most top out at about 1/2 of that value (128 or so). For that matter, with a 16 bit file, most files that I have seen top out much lower than the theoretical limit of 65,000+, more like 1/4 or 1/3 of the theoretical limits.

That puts even more pressure on the files in terms of the resistance to artifacts. The second even minor adjustments are made in PS or other programs to an 8 bit file, you can start to have problems.

I keep the file in 16 bit throughout and never convert down. If you have a need to send an 8 bit file to a printer for compatibility reasons, convert it down and then save it with a unique filename so it doesn't replace the 16 bit version. There's almost no penalty to working with 16 bit files other than file size, so I don't even consider scanning in 8 bit for B&W.


---Michael