Printing Large Photos

[elizabeth_morrissey]

What pixel rate should I print a large photo, say 49cm x 69cm. Is it still 300

per inch? Where is a good place to get that done, online or a chain of some

sort?

[ellis_vener_photography]

You should ask the lab you choose. Try http://pictopia.com/

[JAPster]

The info I've read suggests that 200DPI (dots per inch) is a typical default printing resolution for photographic pictures. If you take the pixel dimensions of your original digital image file, and divide that by the DPI of the Printing Resolution, (say 200DPI), that will give you the dimensions of the resulting photographic print. If you then increase the Printing Resolution DPI, the resulting print will be smaller. And if you decrease the printing DPI, the print will be larger. But the stuff I've read suggests 200 dpi is an unofficial default starting point.

[pvp]

300 dpi is the industry standard for digital files, and you won't ever go wrong by sending your lab a 300 dpi file. OTOH, most people won't ever see anything wrong with a print made at 200 dpi, although sharp-eyed individuals will notice the difference between that and a 300 dpi print.

 

Also, at the size you mention (49x69 cm) people won't normally be viewing the print closely; a normal viewing distance for a print that large would be nearly a meter. Thus you could make such a print at 200 dpi and expect good results.

 

I suggest talking to the people at the lab you choose, and asking them what they recommend for best results; the answer may vary depending on their particular equipment.

[w_t1]

this forum has nothing to do with your question, more of the "digital darkroom" category:

 

 

4x5, 5x7, 8x10 sheet film and digital backs for view cameras

[john_galuszka]

I definitely recommend the 300 DPI standard. I have done prints to 36" wide at 300DPI and at 200DPI and you can easily see the difference.

 

Also, use TIF files, not JPG files--you will get better color accuracy. However, some processors can't handle the latge TIF files, so ask before sending something in.

 

Finding a local printer is better than using on-line or a chain store--being able to talk with the guy/gal who is actually doing the printing is very valuable. For example, for some prints, my guy suggested changing from RGB to CYMK for a slight change which improved the prints.

 

My local printing shop is Lighthouse Litho in Cambria, CA (www.lighthouselitho.com) He just added a machine which can print to 54" wide at 600DPI--so new he is still testing it! I have a 200 megapixel camera which will put his printer to the test at its full capacity, so we will be working on checking everything out in the near future.

 

Send me an e-mail note if you want to be updated on our progress.

 

 

 

John

[a._t._burke]

John Galuszka is right.

 

There IS a difference between 200 and 300 PPI printing. Unfortunately even many of the premium photo printers will try to get away with 180 and 200 PPI printing because the lower resolution that the printer uses the faster the print is made. Time is money. They will look you in the eye and tell you that they did it at 300 when they did it at 200. They will also try to convince you that there is no difference between 180/200 and 300/360. Don't believe them.

 

Also, there is a difference between PPI and DPI. With an Epson wide printer, printing at 1440 DPI it will put several drops of ink in a pixel area when receiving information at 300PPI. There will be more definition from the ink spots in a pixel area as the PPI input number goes up.

[leonard_evens]

There are two issues in printing a large print which you have to deal with.

 

The first is pixelization. Clearly, you don't want to see individual pixels in the print, but there can still be subtle effects if the pixels in the print are large even if you can't see them with your naked eye. That is where the 300 ppi figure comes from. But that assumes you are looking at the print from relatively close up, say 25 to 30 cm. If your viewers are going to get further back, then you can relax some. Roughly speaking, if you divide the viewer distance in cm by 30, you should be able to divide 300 ppi by that factor and still get acceptable results. But since this is only a rough rule of thumb and since some viewers will be more critical than others, you should be conservative about such reductions. If you expect viewers to get close, stay with 300 ppi (or possible a higher resolution).

 

The other issue is how much information about fine detail shows up in the print, which of course is limited by how much such information is in the digital image. This can be complex and is related to how the digital image was produced and what you do with it afterwards. If you scan a film image, it depends on the sampling rate in ppi and the quality of the scanner. Personally, I don't believe that you can make a print that large from a 4 x 5 negative or transparency which won't begin to show loss of fine detail on close viewing, but it would be minor if you had top quality equipment. Again this is much less of an issue if you don't assume viewers are going to be "grain sniffers" who get as close as they can and examine very fine detail in the print.

[keith_lubow]

Call a bunch of labs and ask them. It's their answer that really matters.

 

Keith

[Monophoto]

The term "large format photography" generally refers to the use of film cameras with sizes ranging from 4x5 inches and larger.

 

This post doesn't belong here.

[john_galuszka]

UPDATE:

 

Yes, Mr. Burke is correct, there is a big difference between "dots-per-inch" and "pixels-per-inch", and I should have made clear that I was referring to pixels. Source of confusion: Photohop's scan setting refers to "DPI," but if you scan a square inch at (Photoshop) 600 DPI, you will get a file which is 600 pixels wide. However, if you print that image, the number of dots-per-inch you get will likely be much higher, depending on the capacity or your printer and what resolution you set it to.

 

Therefore, there are two factors you have to take into consideration: the pixels-per-inch of your file, and the dots-per-inch of your printer.

 

I conducted an experiment with Lighthouselitho.com this week. We printed a 300-pixels-per-inch file of a 36" wide photo on two printers: an Epson R2200 which has a DPI resolution of 5760X1440

and a HP 3500CP with a resolution of 600X600 DPI.

 

The Epson print had better color and was sharper when you looked at it from a distance of a foot and a half. (The differences were less noticeable when viewed from an across-the-room distance of 12 feet.)

 

But, same file, different results!

 

So, not only will you have to consider the resolution of your particular file, the quality of the printer used will also have to be a factor to think about.

 

For more on this issue (with illustrations) see the "What you don't see on the Internet" article at www.XtremeDigitalPhotography.com

[Direct link: http://home.uid.onemain.com/~jg1001986/extreme/nosee.htm ]