sluger020889
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Giant Prints

Thu Sep 17, 2009 6:23 pm

I was recently approached by a gentleman who is interested in purchasing a high res copy of one of my pictures for the purpose of printing it at 6 ft by 4 ft. As the picture was taken with a 6 MP D50, I'm a little clueless as to how that may happen. The original is a jpeg, any ideas?

Joey
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clickhappy
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RE: Giant Prints

Thu Sep 17, 2009 7:39 pm

There are a lot of variables, mostly print method and paper type. In a perfect world you would want to print at 300dpi, but have seen decent results as low as 150dpi. To be safe I would recommend 180dpi or above.

The final size you will need will be based upon your target dpi.

6 x 4 is pretty big. You can calculate your file size by dividing the size in inches by the size in pixels. 6' = 96" I believe a D50 is 3008 x 2000 pixels (please correct me if I am wrong)

3008/96=31dpi. Not nearly enough. To reach the minimum of 150dpi (again, this is my opinion) you would need an image that was about 14,500 pixels wide.

Increasing your file size by a factor of 5 is going to result in a pretty marginal image. It would most likely be okay for signage or something viewed at a distance, but for fine art, no way.

I, and others, have used SI Pro (from Fred Miranda) with pretty good results for upsizing.
 
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dvincent
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RE: Giant Prints

Thu Sep 17, 2009 7:49 pm

A six foot by four foot print is probably not going to be viewed up close, though. A good upsampling program like Genuine Fractals should help get it in the ballpark.

Where and how will this print be displayed?
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sluger020889
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RE: Giant Prints

Thu Sep 17, 2009 8:37 pm

Not sure yet on the display, but I did just find the original, and for some reason, even though it was a nice day out, I shot it in RAW, Which i guess can't help.
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sluger020889
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RE: Giant Prints

Thu Sep 17, 2009 8:38 pm

Correction, it can't hurt.*

Sorry for some reason I can't find the edit button.
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flyingzacko
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RE: Giant Prints

Sat Sep 19, 2009 9:13 am



Quoting Clickhappy (Reply 1):
6 x 4 is pretty big. You can calculate your file size by dividing the size in inches by the size in pixels. 6' = 96" I believe a D50 is 3008 x 2000 pixels (please correct me if I am wrong)

Just a small alteration. There are only 72 inches in 6 feet. Therefore 10800 pixels wide is what is needed to reach 150 dpi, how to get the image that big is the real question though, but I guess upsampling, which was said before, should be the answer here.
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iamlucky13
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RE: Giant Prints

Thu Sep 24, 2009 3:16 am

Wait, do you really need another program to upsample? I'm pretty sure Photoshop upsamples by interpolation if you increase the image size. I just did a quick test with GIMP, and it did an ok job when I quadrupled the image dimensions. I think perhaps I could improve it a little more with some noise reduction and sharpening.

Anyway at 48" x 72", I get a 2000 x 3008 pixel native print being 42 dpi. A monitor should be have about 2.5 times as many dpi, for comparison.

Therefore, you can get a rough estimate of what the print will look like (without upsampling) by zooming in on a section of the image at 250% on your monitor. Step back until you can't see the pixelation and let the gentleman know he should be aware that very critical observers standing closer than that distance may notice the quality limits, but you'd be happy to sell the print to him as long as he's aware of that. Most people are so caught up in the scale of an image that big that they don't really know how to look for softness up close.

In my test image, it looks like the pixelation becomes difficult to discern from about 5 feet away.

And while we're on the topic, no existing camera is going to give you 300 dpi in a 4' x 6' print. Even a $25,000 Hasselblad H3DII-50 with a 50 MP sensor is going to print that at barely over 110 dpi. In other words, while a larger source file would be ideal, even professionals deal with the same problem, so don't think your 6 MP source file is a deal killer.
 
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clickhappy
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RE: Giant Prints

Thu Sep 24, 2009 3:44 am

I think what you mean to say is 'no existing digital camera.'

I have had a 35mm transpos scanned at 4000dpi. The file sizes are about 75megs as TIFFs.

When you want to go big, film crushes digital.
 
iamlucky13
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RE: Giant Prints

Thu Sep 24, 2009 7:41 pm

Well, we could go back to the film vs. digital debate, but the nature of a pixel-based image compared to a direct image makes a real comparison difficult. You can scan at as high of a resolution as technology will allow or develop super-fine pitch digital sensors, but at some point the lens is going to limit the usable detail in either medium. At that point, the remaining advantage in film (aside from color and dynamic range which are where film really wins) is the gradual blur from one feature to the next, instead of pixelation.

Anyway, scanning a 35mm at 4000 dpi is actually only going to give you 5670 x 3780 pixels (~21 MP) which is going to print at 79 dpi.

But again, seldom will anyone be critiquing a print that big from up close. And upscaling properly should nearly eliminate the visible pixelation.
 
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dvincent
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RE: Giant Prints

Thu Sep 24, 2009 8:07 pm

Quoting Iamlucky13 (Reply 6):
Wait, do you really need another program to upsample? I'm pretty sure Photoshop upsamples by interpolation if you increase the image size. I just did a quick test with GIMP, and it did an ok job when I quadrupled the image dimensions. I think perhaps I could improve it a little more with some noise reduction and sharpening.

Genuine Fractals is a great program for doing upsamples, better than Photoshop. While PS' upsampling routines have improved over the years, I've seen some gigantic prints made via Genuine Fractals that look very good. Even then, you're not going to be inspecting this with a loupe (it's most likely a banner that will be hung far from the viewer), and viewing distance is very important to keep in mind with printing.

Quoting Clickhappy (Reply 7):
When you want to go big, film crushes digital.

All you're getting with that extra resolution in film is finely resolved grains... There's a certain point where the limitations of your format come into play - though on a good scanner with small grain film 4000 DPI starts to be right around the edge. Besides, a 4000 DPI 35mm film scan (which is normally about as far as I would go) as mentioned above in pixels is not all that much, when you think about it. It's less than modern digitals like the a900/D3x and far less than medium format backs like the P51 in terms of pure resolving power. You still have to upsample just like most digital files and you'll run into the same limitations.

Now, if you scanned a 4x6 piece of film at 4000 DPI... that's different.   I've done drum scans of MF and separations as a Crosfield operator and those are memories that I do not want to relive. Good riddance.

[Edited 2009-09-24 13:26:00]
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