goraggio

I have been trying to have a picture printed on a 3 panel canvas where each panel is 12X18 in. giving a total print area of 18X36 in..
The photo measures 2464X4931pixels and the jpeg. file size is 8.9 mb.
This seems to give 136dpi if each pixel is a dot.
I am being told that the picture should measure 9000X6000 pixels with a dpi of 300 and a file size of no more that 10 mb.

Can someone explain how all these numbers relate and whether my picture can be printed satisfactorily at the size I want? I have had another picture measuring 4975X3315 pixels in a 13.8mb file printed on canvas 30X20 in and it looks beautiful.
This is the file I sent.

photocat Loc: Atlanta, Ga

rule of thumb. Divide the file size (each side) by 200 for an "ok" print. 300 for a better one.

goraggio

What is the number you should get when you divide by 200 or 300 to get a good or OK print?

photocat Loc: Atlanta, Ga

The number you get will tell you the size

I.e. file size is 1200x1600
Divided by 200 will be 6x8 print
Divided by 300 will be 4x 5.33 or 4x6

marcomarks Loc: Ft. Myers, FL

Sounds like the printer has told you how many pixels it takes to achieve a high quality print at the correct pixel count but then wants you to compress the file to send it to them so the file is no larger than 10MB in size, thus you'll end up with JPG compression loss which would deteriorate the quality as bad as having a pixel count that is too low. Don't concern yourself too much with the file size unless the printer has a file size limit you can't exceed.

What you actually want to know is that 300ppi wide X 36 would be 10,800 pixels. 300ppi tall X 18 would be 5400 pixels (half as much). PPI only roughly translates to DPI so 9000X4500 could be a feasible number. Your width to height ratio is 2:1 so the pixel quantity would be as well. 9000X6000 is not a 2:1 ratio so that number is incorrect.

Two things...

First, a wall hanging that is 36" wide doesn't need to be as high in dpi as a handheld paper print to look beautiful because you never look at it up close. You will almost always stand back to see all three panels. That's how a 35mm film frame can be enlarged to fill a whole wall of Grand Central Station or some place like that. The dpi count may be down to 20 or less but you stand back 20 feet and don't even recognize it. The same effect is true of TV pictures too. You think your 1080p HD flat screen is as smooth as glass and photo quality but walk up to it and examine the screen at 18" and you can clearly see the pixel dots.

Your previous 4975X3315 print calculates out to about 165ppi which is not too bad for a print that size being viewed from a few feet away but my opinion is that 136dpi is too low for the one you want to print now. 300dpi is commercial lab requirements. Home printers typically print at 200 to 240dpi. And you're at just a little over half that number at 136dpi. That's not up to the standard I would want.

Personally, if I were going to continue creating these canvas multi-panel large prints that you enjoy, I would buy Perfect Resize 7.5 for $49.95 at http://www.ononesoftware.com/products/perfect-resize/ It used to be called Genuine Fractals and was/is the industry standard way to enlarge any file to create giant prints - better than using even Photoshop. I'm sure this is how Olan Mills Studios can use a 5MP file from old Olympus dSLRs in their nationwide locations to create a crisp 36X48 portrait canvas print in the remote processing lab that will blow your mind.

With Perfect Resize you will be able to enlarge your photos as much as 1000% with no degradation of any kind and even enhance them somewhat too.

Dr Tare Loc: Central California

Thanks for the link, looks like a cool program. Have you used it?
Does it work as good as they say?

photocat Loc: Atlanta, Ga

I have used it several times, and for my needs, yes it does work very well.

imagemeister Loc: mid east Florida

I have two 36 in wide prints made at 150 PPI from crop frame by Fine Art America and they are absolutely gorgeous. I consider 150-155 PPI the Maximum required - in spite of what I read and have been told ! I think 135 PPI will do fine !

goraggio

Many thanks for the clear explanation and for the link. I think any commercial printer worth his salt should be able to resize this for me, don't you?

birdpix Loc: South East Pennsylvania

Take a look at this company's suggestions for resolution for canvas prints. If they think they can get high quality canvas prints at 80 PPI, why can't the company that you are using do it too?

http://www.thecanvasprintstudio.co.uk/canvas-prints-resolution-guide.html

Canvas prints are not intrinsically capable of high resolution because of the coarse texture.

And, finally, yes, your commercial printer should be capable of resizing the image.

marcomarks Loc: Ft. Myers, FL

I have not used it personally but it has been around for a very long time and has an excellent reputation among everybody including professionals. I have seen results of using it but not at the size you are printing. I've seen files only large enough to print a decent 5X7 boosted to 11X14 and 16X20 on regular glossy print paper and they were absolutely fine. So it DOES work as good as they say. I see you're already getting other replies that it does.