Max print size for a given resolution.

[OzzyJim]

Gday,

I have done a quick search of this site and have found a few posts about printer resolution affecting the final size that a photo can be printed at etc, but I want to know if there is any formula to follow when working with photo's and getting ready to print them as to determine bes settings etc.

I have some photo's taken on a 10MP camera that I would like to print at about 6foot x 4 foot and also a picture at my sisters wedding by a pro photographer where he overlaid a photo of them on their wedding certificate. The problem with that photo is that he has resized it to 1316 x 877 and my sister wants it enlarged (unsure exactly how big) and printed. I do have all the photo's he took on a dvd at full resolution (JPG only, not tiff or raw files) and can re-make the photo if needed.

James.

[JohnC]

Too many variables to give a good answer. What printing technology? Inkjet? Lightjet? How far away will the print(s) be viewed from?

For normal print sizes/viewing distances you should be able to get away with 180 ppi. With larger prints that will be viewed from further away you could conceivably go down to 100 ppi and still get a print that looks good at a distance. Think about billboards along the road. Some of those may be printed at 30 dpi or so.

Do you have permission from the original photographer to get that print made? Maybe he has an original that is larger. That 1316x877 file is going to be about 8.7x13 inches at 100 dpi, which probably wouldn't look too good.

For a 4X6 foot print at 180 dpi you will need 8650x10,812 pixels in the file.

[OzzyJim]

Thanks for the info,

I thought it may be a bit to general of a question, but wasn't sure how to ask it. It will all be printed on a inkjet printer, The original photographer has handed over dvd's of jpg's taken (480 odd) and 200? prints and said everyone is free to copy the dvd's and get whatever prints they desire from the dvd. He has no original files left, I would have loved it if he had included the raw files as he has nothing more to do with them now. I do not think copyright is an issue given what he has said.

As for the large 4x6 foot prints my camera only outputs 3872 x 2592 (10mp) - not enough I guess. Am I reading that right?, I would need about a 93 Meagpixel camera?. Is there any tricks to increasing the size without reducing quality too much, I local camera shop once said they had 2x3 foot posters from a 6MP camera.

James.

[swampler]

I think most labs will have software that can upconvert the files better than an individual can. Adorama for instance, states 100 dpi minimum, so you might check around on the really large sizes to see what is required.

If you are going to print yourself, then you might look at genuine fractals...I've heard it's the best way to upsize an image.

[OzzyJim]

Thanks for the info, I do not have a large format printer but may look into the software anyway - I'm sure I could find a few uses for it. I may give up on the 6x4 foot prints for a while and go for a smaller poster size print, I do not feel like (or can afford to) spend out on a digital Hassselblad system for 50+ megapixels of fun.

I will have to play around with some prints (crop end enlarge etc) to see what looks best.

James

[evoryware]

This may help you do the math


Proper Printer Resolution - Digital Photo Pro | DigitalPhotoPro.com

[swanseamale47]

We often make 2x3 foot prints from a 12mp camera, and they look great even close up, but as John says theres a lot more to it than that. Theres 10mp cameras and 10mp cameras, they are not all the same, nor are the lens used, the way the images are processed affects the quality, were they shot on RAW? or jpeg, how much sharpening have the had etc etc.
As for the pros photo, at that size and res it's going to look pretty ropey at 4x6 foot I would think. I'd be supprised if he's chucked the originals, I suspect these are downsized jpegs for normal small printing and that he still has the full size RAW tucked away somewhere.
Contact him and see. Wayne

[OzzyJim]

Gday,

Thanks for the information. The prints from the pro photog were mostly kept at full res jpegs on the dvd but some did vary and the one that they have of the wedding cert overlaid on them was downsized to 1316 x 877. I have contacted the photog and everything has been deleted - no backups. I would think if this was the case and he wanted nothing else to do with the wedding he should have burned the RAW files to dvd too?. My sister wants to get the 1316 x 877 file printed onto canvas, from what I have heard it may not work too well (does anybody have any exp with canvas?).

Wayne, I understand that both cameras and lenses used when taking a photo make a BIG difference in end quality but besides from ISO noise etc does the body make that much difference? (shot in raw so no camera processing). I always thought the glass made the largest diff in quality due to sharpness, Chromatic abberation etc.

I am still learning a lot when it comes to theese things and have been looking at getting the K20D as a replacement to my K10D (I'm a Pentax user). I have also started upgrading my lenses to faster and better quality (eg 28-80mm 3.5-5.6 to a 28-70 2.8 etc). I would love it if Pentax would bring out a Full Frame DSLR, would that make any difference in quality if it had the same MP as a smaller sensor?.

James

[swanseamale47]

The body make a big difference because theres SLR cameras and bridge or compact cameras, all may have 10mp but the sensor sizes will vary greatly, this affects pixle density which in turn affects quality.
Take the difference between say a Canon 450d 12mp and a Nikon D3 also 12mp but no comparrison quailty wise, the Nikons larger sensor make all the difference. Wayne

[chetters]

I don't know if it's too late, but this is a little chart I made a for my cameras.
It's a plain Camera Resolution / DPI = side inches chart.

I put the common DPI prints for my Canon and Epson printers in there so I could quickly see what kind of camera resolution I need to print a particular image size at a particular quality... before software...

The PDF turned out kinda ugly... but I find that this chart was helpful for me in explaining to others how to think about print size.

Maybe it will be helpful to someone else too.

If you want the original, Excel version..
RapidShare: Easy Filehosting

[ukwanderer]

Whilst talking about printing large images, it might be worth taking a look at Rasterbator.
The Rasterbator is an application which creates rasterized versions of images. The rasterized images can be printed and assembled into enormous (or smaller, if you prefer) posters.

Available as an online program for quick use, or download and save the program for future use.

Read the instructions online for converting your Jpeg image to a PDF ready for printing.



The Rasterbator 1.2 at arje.net

[TerryM]

Originally Posted by OzzyJim

Gday,

I have done a quick search of this site and have found a few posts about printer resolution affecting the final size that a photo can be printed at etc, but I want to know if there is any formula to follow when working with photo's and getting ready to print them as to determine bes settings etc.

I have some photo's taken on a 10MP camera that I would like to print at about 6foot x 4 foot and also a picture at my sisters wedding by a pro photographer where he overlaid a photo of them on their wedding certificate. The problem with that photo is that he has resized it to 1316 x 877 and my sister wants it enlarged (unsure exactly how big) and printed. I do have all the photo's he took on a dvd at full resolution (JPG only, not tiff or raw files) and can re-make the photo if needed.

James.

What you ask can be done, IF a good quality camera, shot in raw, and upsized with Genuine Fractals. However, when shot in jpg the quality has already been reduced, and any further manipulation will further reduce it. When an image is shot in jpg it is compressed and part of the data is already removed. Each time it is altered in any way and saved additional data is lost. If the image you want to upsize is jpg and has already been downsized, forget it.

[EOS_JD]

Originally Posted by chetters

I don't know if it's too late, but this is a little chart I made a for my cameras.
It's a plain Camera Resolution / DPI = side inches chart.

I put the common DPI prints for my Canon and Epson printers in there so I could quickly see what kind of camera resolution I need to print a particular image size at a particular quality... before software...

The PDF turned out kinda ugly... but I find that this chart was helpful for me in explaining to others how to think about print size.

Maybe it will be helpful to someone else too.

If you want the original, Excel version..
RapidShare: Easy Filehosting

Nice but your reference to dpi is wrong. Images are measured in pixels and the resolution should be ppi (although I do understand that both are often confused).

[EOS_JD]

Originally Posted by JohnC

Too many variables to give a good answer. What printing technology? Inkjet? Lightjet? How far away will the print(s) be viewed from?

For normal print sizes/viewing distances you should be able to get away with 180 ppi. With larger prints that will be viewed from further away you could conceivably go down to 100 ppi and still get a print that looks good at a distance. Think about billboards along the road. Some of those may be printed at 30 dpi or so.

Do you have permission from the original photographer to get that print made? Maybe he has an original that is larger. That 1316x877 file is going to be about 8.7x13 inches at 100 dpi, which probably wouldn't look too good.

For a 4X6 foot print at 180 dpi you will need 8650x10,812 pixels in the file.

John not sure they are printed at 30dpi? They may be 30ppi images but printed at probably around 300dpi.

I think a 4' x 6' image s possible with a normal 10Mp SLR. So long as you look at it from a reasonable distance it should look fine.

[dicksallee]

Why don't you print out an 8x10 at 100 dpi and see how it looks. You may be surprised at how well it turns out. In any case it will answer some of the questions that have been raised.

[EOS_JD]

Originally Posted by dicksallee

Why don't you print out an 8x10 at 100 dpi and see how it looks. You may be surprised at how well it turns out. In any case it will answer some of the questions that have been raised.

Print at 100dpi? Printing at 100dpi will not result in a good image at all.....

However prining an image saved at 100ppi and printed on a decent printer at anything above 300dpi may result in a surprisingly reasonable print.

Don't get dpi and ppi mixed up as the two are very different.

[dicksallee]

Originally Posted by EOS_JD

Print at 100dpi? Printing at 100dpi will not result in a good image at all.....

However prining an image saved at 100ppi and printed on a decent printer at anything above 300dpi may result in a surprisingly reasonable print.

Don't get dpi and ppi mixed up as the two are very different.

The point of my suggestion was to stop arguing and try it out. If you have not tried it, I suggest you do the same. You may not like the result but at least you will know if you do or don't. On the other hand, you may find that 100 dpi (ppi) is entirely adequate for a large print to be hung on the wall and seen from 5 or 10 feet away.

[EOS_JD]

Originally Posted by dicksallee

The point of my suggestion was to stop arguing and try it out. If you have not tried it, I suggest you do the same. You may not like the result but at least you will know if you do or don't. On the other hand, you may find that 100 dpi (ppi) is entirely adequate for a large print to be hung on the wall and seen from 5 or 10 feet away.

Dick
Sorry but what I was saying was I agree with you. Just that you initially stated dpi instead of ppi. I took your dpi literally as printing at 100dpi which is obviously not what you meant.

I have a couple of very large prints that were printed at 150ppi and look amazing. 100ppi may be a little on the low side for a smaller print but the larger you go the less you wioll notice any difference. As you noted you will probably get a reasonable 10x8 so long as you are not too critical. I normally have enough pixels to print a 10x8 at 240ppi and above so I can't remember trying to print at less but I wouldn't expect the difference to be that huge. Probably acceptable for many except the most critical of eyes.

Cheers
Jim

[dicksallee]

Originally Posted by EOS_JD

Dick
Sorry but what I was saying was I agree with you. Just that you initially stated dpi instead of ppi. I took your dpi literally as printing at 100dpi which is obviously not what you meant.

I have a couple of very large prints that were printed at 150ppi and look amazing. 100ppi may be a little on the low side for a smaller print but the larger you go the less you wioll notice any difference. As you noted you will probably get a reasonable 10x8 so long as you are not too critical. I normally have enough pixels to print a 10x8 at 240ppi and above so I can't remember trying to print at less but I wouldn't expect the difference to be that huge. Probably acceptable for many except the most critical of eyes.

Cheers
Jim

Jim,

The reason I got into this subject was that I read a comment (I can't remember where) from a photographer who suggested not using resampling when upsizing an image. Being in the habit of using one of the bicubic interpolation methods (and being a creature of habit) I, quite naturally, didn't believe him, so I tried it. I resized an image out of the camera to 100 ppi output size (about 30x40). I printed an 8x10 slice of this and, frankly, I was astonished at how good it looked. This was a piece of a portrait and I suspect that a highly detailed image might not fare so well but in this case the eyelashes were nice and sharp.
So I say, everyone's arguing about it - why not just try it out and see?

Dick

[EOS_JD]

Originally Posted by dicksallee

Jim,

The reason I got into this subject was that I read a comment (I can't remember where) from a photographer who suggested not using resampling when upsizing an image. Being in the habit of using one of the bicubic interpolation methods (and being a creature of habit) I, quite naturally, didn't believe him, so I tried it. I resized an image out of the camera to 100 ppi output size (about 30x40). I printed an 8x10 slice of this and, frankly, I was astonished at how good it looked. This was a piece of a portrait and I suspect that a highly detailed image might not fare so well but in this case the eyelashes were nice and sharp.
So I say, everyone's arguing about it - why not just try it out and see?

Dick

Yes Dick. I prefer not to resample too. I've always stated that resampling is either throwing away or adding data that you have no control over. So why do it when most of us can print almost anything that we would need to do up to pretty large sizes.

With a 6Mp+ camera, huge great quality prints are not difficult to achieve without resampling. Everyone is just fixed on this "I must have 300ppi" images to get the best image.

They end up resampling and degrade the quality of their images AND end up with HUGE files!!