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Resizing for print

Discussion in 'Printing' started by DoofClenas, Feb 24, 2016.

  1. DoofClenas

    DoofClenas Who needs a Mirror!

    943
    Nov 9, 2012
    Traverse City, MI
    Clint
    I'd like to get some different thoughts on what is acceptable for printing.

    4608 x 3456 is the native size of my files, un-cropped.

    My rule of thumb is that anything over 24 x 18, I switch to canvas wraps, instead of doing framed prints behind glass. I'll resize/resample my images (in photoshop) to hit 150 ppi. I use CGProprints, and this is what they print their canvases at. Anything at or below that print size I resize/resample to hit at least 192 ppi (the native ppi of the file at that size, if I don't crop any pixels).

    I get that some printers request 250-300 ppi for their files, but will I really notice a difference, given that I won't have my nose up to the print. Do those printers take into account viewing distance.

    Is there a ppi and viewing distance calculator available online? I've had one my 4/3 images used before on a billboard, and moving a 75 mph the less than 30 ppi (pretty sure it was) print looked spectacular.

    Thoughts? What s acceptable for you?
     

    Attached Files:

  2. Wisertime

    Wisertime Mu-43 All-Pro

    Aug 6, 2013
    Philly
    Steve
    150 PPI is pretty standard for canvas. I got some CGpro prints a few months back due to price considerations. They are well put together and priced great, but I think their canvas prints didn't seem as good as simplycanvas...however the subjects were different, though the CG were from EM5/EM1 while the simply were from E3/E30 oddly enough. It may come down to different textures or variables, but CG prices are half what some others are and are good enough. For papers I print 300 DPI and even at 16x20 you can see details up close. I haven't printed bigger, but I'd think 20x30" would be fine...certainly wouldn't think twice about canvas. You can also upsize with genuine fractals or other programs, which I've never used but have been recommended by others.

    I don't know that you would noticed a difference between 192 and 250-300 unless you were printing bigger than 11x14...kinda just a guess. I print at home now and also print from labs.

    FWIW, my 43 prints even from 8mp look just as good as 16mp prints at 16x20

    Red river has some good printing support for specific papers and has color profiles etc.

    Best Inkjet Photo Paper Printer Settings by Red River Paper
     
    Last edited: Feb 24, 2016
  3. Clint

    Clint Mu-43 All-Pro

    Apr 22, 2013
    San Diego area, CA
    Clint
    A couple of things.
    - I do not resize my photos by pixels or ppi when sending to a printing lab. They use a RIP to process prints which are optimized for the printing they do.
    - I've had 36" and 40" long prints made on metal, matte, and gloss - and they look amazing.

    I think you'll find the m4/3s even better than the 4/3 photos we used to shoot.​
     
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  4. DoofClenas

    DoofClenas Who needs a Mirror!

    943
    Nov 9, 2012
    Traverse City, MI
    Clint
    Totally agree...I've got 30 x 40 prints hanging on the wall that I look at everyday...so I get that I can go that big...but what I want to know is what do others do to calculate how big they would print, and at what ppi would be acceptable.
     
  5. tkbslc

    tkbslc Mu-43 Hall of Famer

    If you don't want to do canvas, another old trick is ordering textured prints. Just like canvas, the texture hides the lower DPI pretty well. If you use a high end printing lab, usually they offer texturing for a very reasonable fee (a few bucks). I don't like the way canvas wraps look, nor having part of my image wrapped, and strongly prefer framing. So I usually do large prints, have them add texture, mount it to thin board and then I put it in a large frame with no glass. Looks great and without glass it isn't very heavy.
     
  6. DoofClenas

    DoofClenas Who needs a Mirror!

    943
    Nov 9, 2012
    Traverse City, MI
    Clint
    I found this formula that calculates ppi based on viewing distance, but I have no idea if it's accurate:

    The formula is ppi = 1/((distance x 0.000291) / 2)

    Viewing Distance (inches) Resolution (ppi)
    6" 1145 ppi
    10" 687 ppi
    24" 286 ppi
    36" 191 ppi
    60" 115 ppi
    120" 57 ppi
    600" 11 ppi

    EDIT:
    It appears to accurate, based on what I've printed in the past.
     
  7. tkbslc

    tkbslc Mu-43 Hall of Famer

    That looks like the formula for maximum DPI the eye could resolve. Meaning, there is no point in printing higher resolution than that because your eye can't see the difference.
     
    Last edited: Feb 24, 2016
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  8. My favourite 40" canvas print is also the lowest resolution image that I have had printed at that size, which is from a Canon 350D cropped to a bit under 7mp. That probably makes it 70-something ppi and I remember getting a warning about the low resolution when I uploaded the file. Glad that I ignored it!

    Notwithstanding the ability of canvas to handle lower resolutions, I also prefer the looked of a wrapped canvas for larger prints. Large, framed images seem too formal for me, and from a practical standpoint are heavier and require stronger anchoring to a wall.
     
  9. bjurasz

    bjurasz Mu-43 Regular

    127
    Dec 10, 2014
    Cedar Park
    I've done 20x30 prints from the 8MP days without resampling or uprezzing or anything like that. At normal viewing distances zero issues. Who really looks at a print that large from a few inches anyway? One of my favorite prints ever was from a Digital Rebel taken with a 50/1.4 lens on a tripod. Cropped to 5 MP and printed 16x20 it was stunning and detailed. People massively over-think the whole DPI thing when printing.
     
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  10. dwig

    dwig Mu-43 Top Veteran

    622
    Jun 26, 2010
    Key West FL
    It used to be that upsampling was a black art requiring mystical incantations. These days the RIPs used by most printers to drive their large format printer do an excellent job on their own. With many labs/printers, in most cases there is no need to do your own upsampling. The lab's/printer's RIP will do it on the fly and do it well.

    That said, even though we use a very good RIP (ImagePrint by ColorByte) to drive our 44" EPSON printers, it is our gallery's convention to upsample our print files in Ps before sending them to the RIP. Our choice is to upsample to 300ppi at the final print size. In casual testing I can't prove that 300ppi is better than 200ppi on canvas, expecially when printing large canvases.

    By doing the upsampling in Ps we can review any flaws that show at the new larger size and do the necessary retouching. I often encounter some minor flaw (dust spot, scratch, grain clump, imprecise adjustment mask, ...) in the original adjusted image (most are from film scans) that may have been invisible in smaller prints but noticeable when resized to 40-60"w (our most common size range) or larger.
     
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