printing on traditional photographic paper

[cap]

Can anyone tell me what resolution is needed for getting prints made on traditional photographic paper (NOT from a computer print-out) -to the same quality as prints from negatives?.

I haven't got a digital camera but am considering getting negatives put onto a photo cd (at 3072x2048 resolution)

[neilp]

Hey cap,

welcome to photozo.... i see this is your first post....

unfortunately I'm not sure I quite understand what you mean. Can you be a little more specific???

If you get your negatives scanned at 3072x2048 that's about 6 megapixels. There's many different views on what resolution is the same as a 35mm negative but it's often said that 6 MP is about the same detail as a 35 mm negative so if that's what you wanted to know then I hope I've helped!

neil.

[cap]

basically, I want to know what would be the largest sized print I could make at a resolution of 3072x2048 (while still being as high quality as a print made from a negative)

I'm also assuming (please correct me if i'm wrong) that if I took the image to a professional lab to be processed on traditional photographic paper that I would need a higher resolution than if printing out on a computer printer, as it would be printed at a greater resolution (dpi) and therefore show up the pixels more.

(though from what you're saying it sounds like this is quite a high resolution - are you saying that scanning 35mm negatives at higher resolution than 6MP wouldn't increase the quality as it would have already reached the limitations of the grain of the film?)

[aweller]

Cap ... there is not one simple answer to your question.

It depends on the device you (or the lab) are printing to and the paper you are printing on.

It depends on the process involved in the printing .. perhaps even "pre-press".

The lab I print at has a Kodak LED Pegasus printer. It is a 250 dpi printer. It is a photographic process but ultimately driven by software.

The latest Konica mini-lab - the R2 is a 400 dpi engine. Perhaps it is better? but it can only do up to 10x15". Most of the older mini-labs that you find in your "corner store" labs are lesser - even down to 180 dpi.

Then again, you can get the Epson R800 ink-jet printer which prints at 5760 dpi allegedly.

this means you can print you 3000x2000 image in about half an inch square "native" resolution!

(and I am sure there is a lot in between).

You decide for yourself based on the quality of the output, but be assured garbage in, garbage out, and the people operating the equipment need to know a lot about colour digital output to get the best out of any equipment - you at home, the school kid sitting at the mini-lab all night doing happy snap after happy snap, or the "professional photo engraver" - or what ever you call the guy who has been doing this since Adam was a boy, is fully trained and experienced with the digital process, and knows his stuff.

To get stuff on a photoCD you only need a scanner - perhaps one of the fancy new transparency scanners to scan your original material, depending on what you are doing, or perhaps, your finished prints.

Generally speaking, if the lab is any good, they will get the best out of the images you give them. They can''t make something out of nothing ... but expect to pay for the effort someone needs to put in.

If you understand Colour spaces and the capabilities of the input, working and output devices, you might be able to get a little smarter, and do the work yourself, and still get a quality product, but don't expect it to work without effort, or to be simple to understand.

At the end of the day, it is what the eye perceives that matters.

I have dozens of 6MP files blown up to 30" x 20" - probably bigger than I would have been happy blowing up 35mm work in the past. But if your 6MP are full of noise, or the native resolution of your scanner was too low, you will get crap whatever size you are printing.

hth,
Andrew who finds that labs HATE talking about dpi for some obscene reason.

[neilp]

Hey Andew... some great info there!

Cap - yes what I'm kinda saying is that many people believe a 6MP camera gives very similar 'resolution' to the 35mm neg due to the size of the grain. Now I don't know what speed that refers to but the theory goes that you should be able to enlarge your 6MP digital image to the same size as you would a 35mm negative.

Now while the detail may be the same there's clearly a difference between the shape of the 'grains', i.e. the digtal ones are square and pixel-y but the film has a more random grain which may be more pleasing to the eye when englarged. If you are going to make a BIG print, then the best thing to do is to enlarge it some more on your computer first, the computer can then do some interpolation (give you more pixels and work out what should be in them) search around on photozo for some hints and tips. Also take a look over fractal image englarement.

One other thing to note - you can't really compare a inkjet printer with 5000+ dpi to a photographic printer with only say 300 dpi. There's a huge difference in the way they work, i.e. the inkjet needs lots of dots of the limited 3 or 6 colours it can print to make the range of colours you want. Whereas, the photographic printer at 300 dpi can make ANY colour at each dot by some kind of colour laser scanning on to photosensitive paper. The resoloution sounds low but in fact it's effectively the same or better, and there's no dots when you look up close!

Hope this helps!

Do some google searches and also photozo searches and see what you find. There's definately articles about these things around. If you find anything good then post a link on this thread!!

Neil.

[aweller]

Hi Neil,

Well sometimes ... there are 8 colour printers now from Epson and HP (at least) and by some (allegedly) independent tests - better quality reproduction than professional labs.

Resolution is one issue.

Colour reproduction is another.

They are related, because the range of colours that can be used increases the effectiveness of anti-aliasing.

Lastly, interpolation on your PC is not necessarily better than the interpolation on the (perhaps) more expensive software on the lab's equipment.

hth.
Andrew.

[neilp]

Yep - you're definitely right on that last point - it's more than likely that when the lab enlarges and interpolate your image they'll have a good system setup.

I'd be interested to know the difference in colour space, gamut, between a photographic print and an ink jet print. Anyone know?

Neil.

[aweller]

Depends on the inkjet.

HP claim their best is better than the best photographic processes for colour space and vibrancy.

[milehidweller]

Returning to cap's question - The way I see it:

What is relevant here is the grain size of the photo-paper.
Assuming it is the same for negative prints and digital prints,
you want your digital image resolution no less than the paper
grain resolution.
For ordinary run-of-the-mill color prints it is widely accepted that
resolution of 150-200 dpi is sufficient for scanning, therefore it is
safe to assume that the grain size is somewhere in that ballpark.
Hence, same resolution should be good enough for digital prints too.
If you crank it up to 250-300 dpi results should undoubtedly be
undistinguishable from negative print.
You can see now where this puts you: 12x8 prints from 3Kx2K scan
should be excellent, 15x10 prints still may be almost as good as
negative prints.
And that is almost the limit of 35mm color film itself.

Just 2c from nobody in particular.

[Landis]

Surely there are many ways to think about this. A lot depends on what surface paper you are printing on (ink jet) as a glossy paper will appear to be sharper then a matte paper. I print on matte paper almost all the time and have found that I upsize my images in the computer to the final size at 300 dpi. I have tried it at higher resolutions and have found that I cannot see the difference on the final print. I usually print out at 720 dpi, but sometimes go to 1440 dpi on the final print. Anything above that is overkill. On a glossy paper, I have printed out at 2880 dpi a few times and that is great, but not necessary in my opinion.

I have found that with careful upsizing of a sharp image, I could get REALLY sharp prints as follows:
6mp original to a max of about 12x18"
11mp original to 17x21.5" at Super Sharp, but up to 24x36" very sharp.

You also have to realize that when you get up to the very large images, you are not going to be looking at them from 8" away, but at a viewing distance much greater, so sharpness is not such a critical factor, just as you don't judge the sharpness of a bill board on the highway from 3 feet away.

It's all a very subjective subject, so there are 1000+ opinions on the matter. So, don't :bang: , relax and have fun.

[Mike Hall]

Sounds more like cad was asking for a rule of thumb.

I asked my photo printers this question a while back, and they came back with the same confusing list of terms - they have a 400dpi printing lab, explained the paper type, and how compression on the image will affect image quality as much as resolution, blah, blah.

But they did tell me that the rules weren't hard and fast - if you're looking for a print out then this might be helpful :

6x4/7x5 - minimum for ok print 2 megapixel recommend 3 megapixel
8x6/10x8 - minimum for ok 3 megapixel recommend 4 megapixel

Saying that, I have a 3 megapixel camera (I use the lowest jpeg compression settings - i.e. largest files) and I got them to print some images for me on 12x8 and they were really super, so it's subjective.

I get my pictures printed at fotoserve.com (click here) (http://www.fotoserve.com/). They have even bigger sizes now - I'm going to try getting a 3 megapixel image printed up at 20x16 for my wall to see what its like.

[Landis]

That should work fine at that size. Try to use the lease compression possible if shooting JPG's. I always shoot RAW then convert to TIFF. Then again, there are many opions on all that, as there is not one "right" way to do it.