Cropping, ppi and size for printing?

[Aylwin]

I'm starting to frame some of my printed photos and I have a few questions.

Cropping:
The action itself is easy. However, I've noticed that if my cropping is too exact then I lose some detail when I mount on a picture frame because there's some cropping there too (a bit on the sides are hidden behind the frame). What do you guys do? Any guidelines? Do you, for example, leave 1 cm (or half an inch) all around? Is there like a standard for picture frames?

PPI and size:
I've read on other threads that 300 ppi generally gives the best print. For the 10D, that's roughly 7 x 10. For 8 x 10 prints or larger, you can resize or decrease the ppi. How about for smaller prints (eg. 5 x 7)? Do you downsize or increase ppi? Or do you leave it as is and let the printer "scale to fit"? I'd imagine having the exact size and ppi would produce better results (eg. 1500 x 2100 @ 300ppi for 5 x 7 print). Or does it even matter if the prints are small?

Professional prints:
What if I have prints made at the local Kodak or Fuji lab? Do they take into consideration the embedded file info or does their machine simply scale to whatever size print you want?

Thanks,
Aylwin

[Scottes]

Cropping: I'm still trying to figure this one out. My printer (camera lab) crops about 17 pixels from all sides on a 4x6. But I've found that their printer is 400dpi while I've been preparing at 300dpi. The cropping may be due to the fact that the printer now has to interpolate my image. So I have a couple more tests to do. Also, I've heard that some places expect a white border and they will crop to that border. Alas, I have no more info than that, which is pretty thin but might be worth a test with a 10-pixel border on all sides.

PPI: Yes, 300 is generally accepted to be very good - for prints that will be held close, like a 4x6. As the size gets larger people generally hold the image further away, so the PPI can be lowered. Images like 20x30 could go down to 180 PPI since people will not be that close when they see the image.

Prints: These machines will generally scale so the image gets printed at the PPI of the printer. For this reason I like to give them the image at the same PPI. So when giving them something to be printed at 5x7 @ 300 PPI I will prepare a file to 1500x2100. This gives you the most control over the image since the printer won't possibly "damage" the image by interpolating to their desired size. This isn't always easy, since a 20x30" is now 6000x9000 pixels, and begins to take a bit of RAM on the PC.

Places using Fuji & Kodak printers are generally using photo printers and are really fairly simple when compared to high-end "pro lab" printers like a Lightjet. Photo printers will generally expect a 300 PPI image saved in sRGB JPGs - I had some problems getting 16-bit print TIFFs printed and I now use 8-bit JPG since these (all?) printers only print at 8-bit anyway. They may accept 16-bit, but printing at more than 8-bit would be extremely rare, I'd think, since the color gamuts are much smaller than a monitor's.

If you do give them an image that you've prepared and saved as sRGB you will want to tell them not to do any color-correction. The printer may adjust for what he thinks is right, and this generally ends up being over-saturated since the general public likes their colors to "pop" with some over-saturation.

In any case, I strongly suggest checking out the people running the system. Ask about the system, and see what they know. Generally I just ask about PPI and color profile. If they know what a color profile is and can recommend settings to you then you've hit a gold mine for a photo printer. If they have no idea then I give them sRGB.

Finally, after finding someone who knows what they're doing, run some test prints through. $5 worth of 4x6 images will teach you a lot about how to prepare images for them. And be sure to try different sharpening settings - printing pretty much requires "over sharpening" when viewed on a monitor. View the prints at slightly different distances, too - you won't normally hold an 11x17 up to your face, so view it from a couple feet away.

[Aylwin]

Oh no, this is worse than I thought! :shock: I was just worried about mounting the prints on a frame. I simply assumed that what I send for printing is what I get back. It never occurred to me that there's cropping at the lab too. :(

Thanks for the info and advice though. It's very helpful. I'll do some experiments and try to speak to the lab people. Problem is, it's not easy to communicate in Japan if one doesn't speak Japanese.

Anyway, I guess one important thing I've learned just now is that I shouldn't compose my shots too tightly. It seems I should always leave a bit of allowance for cropping due to whatever reason. Also, it seems cropping for web presentation is considerably different than cropping for printing.

Perhaps you could include what you've explained to me in your excellent series of tutorial threads? :) Perhaps you could put together something along the lines of "Preparing photos for printing".

And on that topic, I have a few more follow-up questions from your explanations above:

For a 4x6 print, it's best to prepare a 1200x1800 sRGB image @ 300 ppi. But then, to account for cropping let's say we add 10-20 pixels on each side. Should I therefore prepare an image that's somewhere between 1220x1820 and 1240x1840?

Would you recommend using Save for Web? To me, Save for Web seems to do a better at size reduction than Image Size. Plus, it automatically converts to sRGB. Is there a better way?

Printing with own printer:
If I print with no borders, I assume I follow the same as above. What if I print with borders? I should then prepare images that are smaller, right?

The more I think about all this, the more complicated it all gets. :roll:

[Scottes]

Sorry, I didn't mean to alarm you, but rather to explain the issues that I've run into. It's really not all that complicated.

Simply put, prepare a 1800x1200 @ 300 dpi image, convert to sRGB, and save as JPG at maximum compression, and bring this to the printer. Use File... Save As JPG at maximum quality. Save For Web gets you nothing, takes an extra step and time, and may actually cause problems if you don't have a setting right.

If you have an image where the subject is *very* close to the edge then you *might* find an image cropped. Save such an image for your second run to the printers - check the first run to see if they are cropping at all. My cropping may have been because I prepared a 300 dpi image for a 400 dpi printer. If they *are* cropping, 1240x1840 would be my bet.

If communication is difficult, sneak a peek at the printer and research it on the web. But sRGB at 300 DPI is a very safe bet for a photo store.

If you tell them to print with borders then you can make the image a bit smaller. They'll resize slightly to fit in any case.

This is an excellent idea for a tutorial, but I've just been so busy...


Again, it's not that difficult. Do a test run of 5 or 10 images and you'll have it down.

[tarves57]

[quote="Scottes"]Cropping: I'm still trying to figure this one out. My printer (camera lab) crops about 17 pixels from all sides on a 4x6. But I've found that their printer is 400dpi while I've been preparing at 300dpi. The cropping may be due to the fact that the printer now has to interpolate my image.
quote]

Scottes, you are a minefield of information!
Thanks very much for your extremely informative answers! You are a gem.

Susan

[Malok]

Scottes, Your explanations were fabulous. You answered a number of questions that I have had. I think that many of us who want to get back the very best quality prints have these same questions. I agree, that this would make a really good tutorial if you ever find the time.

Many thanks!!! :D

Malok