resolution and dpi for enlargements - confused a bit

gginsocal · Dec 11, 2012

What would make a better 11x14 print: 2400 x 3600 at 250 dpi OR 2400 x 3600 at 300dpi? How does the file size matter/affect the print? I was given a usb drive from a photographer that compressed my purchased images of my newborn and family so I cant make quality enlargements unless I order from her. She said she supplied the images at 250 dpi, but the properties say they are at 300 dpi at the above resolution. From what I have read about dpi, I am a little confused as to which would make the best 11x14 print. It seems as though what was provided was morefor a good 8x10 print. But it seems like everyone prefers 300 dpi for printing. One of the files was only about 750 KB. The others were approximately 1.2-1.5 MB. It also looks like the focus was softenedhow will this affect print quality?
Being a beginner in my own photography, I am trying to learn from the experience of purchasing my family images from someone else. Any insight would be helpful as to this question and any helpful recommendations when going to print. Thanks!

christop · Dec 11, 2012

DPI means Dots Per Inch and usually refers to how many dots of ink per inch a printer can lay down on paper. Since we're working with digital images, we use the measurement Pixels Per Inch (PPI) to indicate how many pixels from the image fit inside an inch of paper when printed.

The math is simple: divide the number of pixels by the number of inches.

3600 / 14 = 257.14 PPI and
2400 / 11 = 218.2 PPI

We want to keep the image aspect ratio correct, so we have to crop the image a little bit in the long dimension and go with the lower resolution (218.2). 218.2 * 14 = 3054.5, or 3055 pixels if we round. So you end up with a 3055x2400 pixel image printed as a 14x11 inch printout at 218.2 PPI.

Generally you want to print at 300 PPI or higher, but you don't have a large enough image to achieve that kind of resolution at 11x14. On the other hand, at normal viewing distances of a 11x14 photo, 200 PPI should be good enough.

pgriz · Dec 12, 2012

Perhaps a better way would be for you to purchase the images from the photographer at the size you wish to print. Pretty sure that the images given to you on the USB drive were to allow you to review the images and decide which of them you wanted to order, ie, they were "proofs". Once you communicate that desire to your photographer, they would then generate the images at the right resolution for printing at a specific size. If you are trying to print large images from proofs, then you are potentially violating your purchasing agreement (and their copyright) with the photographer.

gginsocal · Dec 13, 2012

Thank you for your replies....So it sounds like I may be learning the hard and costly way. This is a lot of info, but maybe someone can tell me if I have this right (In other words, did this photographer completely rip me off and make it so I couldn't print a good quality enlargement comprable to hers??

Here are the details:
The usb drive was purchased for $800 for 10 images with a printing release and definitely were not proofs. To give you an idea of her high prices/ markup: $140 for an 11x14 mounted on styrene and $240 for a 12 x 12 mounted. These family and newborn prints were supposed to be framed gifts for family and small enlargements for our house and therefore needed multiple prints. She says her pro lab is the only lab that does a good job (she won't tell me the name of the lab) and therefore that's why she justifies her high print prices. I have received one 11x14 print from her (from her photo lab and included with my sitting fee) and it was very crisp, clear and looked just like the computer monitor.

She did tell me that any enlargements higher than 12x12 or 11x14 wouldn't print well and I would have to order through her and pay her prices (essentially holding my pictures hostage). I just wanted my images of my family and then not to use her again, so I paid the $800 with the understanding and her promise that what would be provided would produce quality 11x14 and 12 x 12 prints...her disclaimer was that she was not responsible for bad print quality at any lab. She did recommend MPIX as a consumer lab to go to, but it sounds like the file size won't suffice and the image quality will be lost with her amount of compression. (also the image for the 12x 12 was provided at 3600 x3600 at 300 dpi/ 1.78 MB)

I know there are several quality labs out there and there shouldn't be such a discrepancy in quality if using a good lab. I printed several of the images she provided to a local lab. At the same time that I also finally got some wedding picture enlargements. The wedding enlargements turned out beautiful and looked just as appeared on the monitor (also from a usb drive but the file sizes were all between 5-6 MB and the resolution was a bit higher). Her photographs from the usb drive turned out with shadows, not as sharp, with definite loss of quality and not nearly as good as the monitor. Again, this is the same exact lab, 2 different results. The lab even reprinted some for me while I was there to counteract the above issues, but with very little improvement.

So I'm feeling very frustrated, ripped off and kind of stupid that I didn't know what to look for and ensure prior to purchasing from her. Any suggestions? I've concluded it's the file size, but is this correct in anyone else's opinion? Is there anything else to consider? Thank you in advance for your time in reading this and any insight- just want as much info as possible when I approach her in either getting the appropriate image files or my money back.

KmH · Dec 13, 2012

Those are pretty much normal professional photography business practices.

I charged $155 for an unmounted 11x14.
The cost of a mounted 12x12 would vary based on the mount material.
There is no where else in the world where you can get images made by that photographer.
$75 each for edited images on a disc is about standard.
Many photographers that charge less, and use less sound business practices, aren't in business very long.

(essentially holding my pictures hostage)

If you're here in the USA they aren't your photos, because the photographer is the copyright owner. That's what the print release all about. It's a license issued by the copyright owner that grants you restricted usage, in this case making prints.

Commercial clients often get a more complex and involved license which defines exclusivity, media types allowed, geographical usage restrictions, and time restrictions.
Commercial use licenses are usually an addition cost beyond what the photographer charges to make the photos.

gginsocal · Dec 13, 2012

Thanks for your reply and insight, Keith......Let me simplify my questions (and take my feelings out of this)....So within the print release which states that the images provided will "produce a quality image up to 11 x 14" - is the file resolution and file size enough..I've been told that 753 KB is inadequate. (see my above posts)? And is there any reason why in her release she stated the "images are color corrected RGB at 250 dpi" but the properties say they are at 300 dpi?

The_Traveler · Dec 13, 2012

let's start a bit from scratch.

(first note that pictures come in 4 x 5 ratio ( makes 8 x 10 or 11 x 14) and 4 x 6 ratio (makes 8 x 16 and 12 x 18) and square. Thus the sizes in pixels are in that ratio)

It is the size of the image in pixels that counts so you needn't worry about the figure per inch or dpi.

typically pictures are printed at 250 or 300 pixels per inch to get good quality

so - if you want a decent 11 x 14 - you would need at least 11 (* 250) x 14 (*250) or 2750 x 3500.

There is another issue and that is the amount of compression - which sort of determines the quality of the detail in the images.

A higher quality (less compression) file of the same physical dimensions would be larger in bytes.

For example, the picture below, saved for an 11 x 14 with a compression that I would use to print, would be about 2 megabytes.

The_Traveler · Dec 13, 2012

Re: the printing.

MPIX is a decent consumer lab and there are lots and lots of others, including Costco, that will do a good job.

Please remember that her costs are not actually a reflection of the print cost to her but were a price to take the picture and provide them to you, just as the cost of a car repair is not just the actual value of teh parts installed, if any.
There is service, skill, experience and capital costs that must be amortized.

All that being said, did you have a contract that defines what your receivables were?

christop · Dec 13, 2012

gginsocal said:
And is there any reason why in her release she stated the "images are color corrected RGB at 250 dpi" but the properties say they are at 300 dpi?

The dpi value stored in the file metadata and what the photographer told you about the dpi are irrelevant. The file metadata could say the picture is 3 dpi or 30 dpi or 3000 dpi; it doesn't matter. All that matters is the number of pixels (image resolution) and the number of inches (print size).

Perhaps she gave you an approximation based on 3600 / 14 = 257 ppi, but that would give you a printout that is only 9.3 inches on the short side rather than 11 inches.

panblue · Dec 13, 2012

200ppi could be enough for this.

KmH · Dec 13, 2012

Pixels-Per-inch (PPI) become relevant when printing, because along with the pixel dimensions PPI determines the print size.

3600 pixels divided by 257 pixels-per-inch = 14 inches (the pixels cancel leaving only inches)

However, print labs use RIP software (Raster Image Processing) that will adjust the PPI to produce the appropriate print size. But, print labs generally have a minimum PPI they will print at.

Mpix no longer has a web site page that describes their requiresments, but when they did they staked their reputation on a 100 PPI minimum limit, and noted that their chromogenic printing process had a max limit of 250 PPI.

gginsocal · Dec 14, 2012

It is now becoming much more understandable between everyone's explanations....this has been really helpful so far.... Lew- The receivables per the contract were one 11x14 print mounted on styrene per session and the time, creation fee, etc....this was for $275 per session for 2 sessions = $550, plus ordered one print plus paid $800 for the 10 USB images, 9/10 images were from the second session. (and tax on everything of course).

So it sounds like I need to request at the very least: 2750x3500 for a good 11x14 at at least 2MB and this will also avoid any cropping and the image ratio is left intact? And ideally, I should request 3300x 4200 at at least 2MB? And I don't need to worry about the dpi.... (am I getting the hang of this?)

The_Traveler · Dec 14, 2012

yes,

This is a no-lose for her.
It's nothing to export new higher quality (lower compression) images and I can't imagine she would balk at this.

gginsocal · Dec 16, 2012

So the photographer re-sent the images. I requested them at a minimum of 2 MB (and 3 MB for the square prints) and resolution to print at 11x14 and 12 x 12. Now I'm a bit confused about what she sent and why. Most of the images were increased in resolution, but the file sizes were DECREASED in some cases or very minimal increase.

She stated in her email "I just am sending the main files. This is only because of the problem you are having (with printing)." Here are some examples of file size she gave me:

#1- originally gave me 1.38 MB -2400 x 3600, now 1.48 MB - 3840 x 5760
#2 - originally 753 KB - 3600 x 2400, now 927 KB -5760 x 3840
#3 - originally 1.3 MB - 3600 x 2400, now 1.05 MB -3292 x 5760
#4 - originally 1.44 MB - 2400 x 3600, now 2.28 MB -3840 x 5760 (the only one markedly increased in file size)
#5 - originally 1.78 MB -3600 x 3600, now 930 KB -3840 x 3840
#6- originally 2.3 MB -3600 x 3600, now 1.17 MB - 3769 x 3769

Very inconsistent. Not sure what is going on here? Just when I thought I had the hang of this, this was presented. It seems to me (from all the education on this thread) that the file size will not support the resolution (and why are the file sizes decreased now?). Is there something about compression/settings to understand? Any thoughts??

The_Traveler · Dec 16, 2012

If the size of the file in bytes is decreasing while the dimensions in pixels are increasing, assuming no other oddities are going on, this implies means that the compression is increasing and thus the quality is decreasing.
This may not affect the image when printed but surely is unexpected.

Lew