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I always have a hard time when preparing my photos for printing at a lab; especially large format.

I wanted to print out an 11"H x 14"W recently and I started reading and reading and reading. According to this I needed to crop the picture to a ratio of 11:14. That part made sense and that is what I did. During the export, there is a box labeled resolution. This is the aspect of printing that always confuses me. According to this chart I can expect "Superb" quality for an 18MP camera for images 11" x 14" with a DPI setting of 350.

Using both of those two links, during the export I resized the image via the dimensions option to 11 x 14 and set the "resolution" to 350pdi.

Is this the correct procedure? Can I expect a "Superb" print doing it like this? If not, where did I go wrong?

The picture was captured with RAW using a Canon 7D. I am using Adobe Lightroom 4.

UPDATE

Both answers mention down-sizing. Is that the act of changing the dimensions during export?

My biggest hangup currently is the DPI. Any printing I might do, I just want the DPI to be the number where no information needs to be added or removed by the software. I guess the native DPI of whatever pixels are left over after the crop is what I'm trying to achieve.

UPDATE 2

Assuming my image output is 4399 W x 3456 H after the crop. If I want to be sure that the printed DPI will be 300 or more, if I do 4399 (cropped side) / 14 (inches of the print I want to make) = 314.214. To me, that means that the photo at that resolution will yield a print at over 300dpi. Is that all there is to it or am I missing something with that calculation?

Zero21xxx
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    Related Q&A:

    http://photo.stackexchange.com/questions/4779/what-dpi-should-i-resize-my-image-to-for-best-printing-quality

    http://photo.stackexchange.com/questions/456/is-there-a-general-formula-for-image-size-vs-print-size?rq=1

    http://photo.stackexchange.com/questions/20856/how-large-an-image-do-i-need-to-print-a-32-by-18-poster-at-300-dpi?lq=1

    http://photo.stackexchange.com/questions/1652/how-do-you-optimally-resize-and-sharpen-images-for-printing?rq=1

     – MikeW Sep 08 '13 at 20:02
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    The grandaddy of all printer related quality questions: http://photo.stackexchange.com/questions/1715/how-do-i-generate-high-quality-prints-with-an-ink-jet-printer/1716#1716 – Michael C Sep 08 '13 at 20:26
  • From your updates, I think that the posts that MikeW linked to should really help. Have you checked them out? – mattdm Sep 10 '13 at 20:54
  • I did read the provided links and updated my question see Update 2. – Zero21xxx Sep 10 '13 at 23:53

2 Answers2

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You absolutely have to do the crop because it is an artistic decision.

Downsizing is best avoided, unless you have some file-size constraints. The reason is that it has to be done at the printer-level which work in a completely different way than digital camera pixels. If you resize first, you add a second level of resampling which at best will not make things worse.

EDIT to address your update: You see, print size, image size (commonly called resolution) and DPI are related. You cannot set all three. If you want no resizing to happen, you cannot set resolution because that is the image you have. You can set print size because that is the image you want. Therefore, DPI just falls where it must be. Leave it unspecified and it does not matter. If you really want the right number there, then divide the image size by print size on the uncropped size dimension. In your case, 3456 pixels / 11 inches = 314 DPI.

Itai
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This is not the correct way to go about it. The crop is necessary for the obvious reasons which you already seem to understand. The DPI however is a guideline for how much image data must be exceeded. In most cases (unless the printer can't handle high DPI images, which is exceedingly rare these days), you are fine to submit an image with a higher DPI than that which is required. The value of 350DPI for superb prints (most quote 300ppi) is simply a measure of how much information is necessary for us to not see the pixels when viewing the image from some arbitrary distance. 300PPI(pixels per inch) lets you get pretty close to the image (arms length or closer) before it is a problem.

If your image is lower quality than this, up-scaling it (increasing the PPI) isn't going to help much as the information isn't actually there, it's just being created based on the existing image data and won't add anything (you might actually lose a little.) Similarly, if your PPI exceeds the requirement, decreasing it is not necessary as pretty much every printer can down-scale based on the actual DPI and dot pitch that it is going to print. The higher quality the source, the more accurate it can do with the down-scaling.

The only time that down-scaling is really necessary is if either a) the printer being used does NOT support down-scaling (pretty rare) or b) you know the exact DPI configuration of the printer and want complete control of the way the image is scaled to be able to apply corrections to the final output resolution (unnecessary unless some weird artifacting occurs in the downscale, which is also rare.)

AJ Henderson
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  • @Zero21xxx - the point is don't worry about the PPI (pixels per inch, DPI refers to the dots printed by the printer and is typically much higher). You will have whatever you have. Crop the image the way you want, look at the PPI you are left with. Choose print size according to taste within the upper limit set by the sharpness of the image and the PPI level appropriate to your viewing distance. If after you crop the image you are left with an image that is 150PPI at 8 by 10 and is blurry, then you aren't going to get a good 8 by 10. If it's sharp and 350, it will be gorgeous. – AJ Henderson Sep 10 '13 at 13:15
  • @Zero21xxx - when you adjust the height and width, it will not alter the pixel count (unless you specifically tell it to) and thus the pixels per inch will be updated to tell you how much information is actually there. – AJ Henderson Sep 10 '13 at 13:16