File prep for large print sizes: How to do it and How does it work?

[Pegasus_Thrust]

I have recently had/still have to a certain degree an issue getting my photos up to resolution for large print sizes for clients to order direct from 3rd party vendors (One vision) through zenfolio.

I am exporting my files from LR in most cases and the files are coming from a 12mp D3.

I potentially have had a breakthrough with this though as I have set in my export settings to have the pixel H x W the equivalent of 300dpi for a 36 x 24 inch ie. rather than it be 4000 x 3000 it's now 10800 x 7200.

But this has turned my world upside down from a technical perspective.
Surely the 12mp my camera bangs the images out is as good as it gets?.... if files on that basis aren't cutting the mustard when it comes to resolution for large printing then surely it's gameover?...... I can't see why have LR perform jiggery pokey in the exports changes the rules and how for all intensive purposes it "magics" extra pixels out of thin air?

I am probably missing something with all of this, I do hope there is someone out there that can shed some light on it!?

Thanks in advance

 

[StewartR]

I am probably missing something with all of this, I do hope there is someone out there that can shed some light on it!?

I'll have a go.

First of all, 12 megapixels from your camera is plenty for a good 36" x 24" image. Obviously it will look very slightly pixellated if you inspect it very closely, but from any kind of normal viewing distance it will look fine.

Now if the printer prints at 300 PPI then it needs to have 10800 x 7200 = 77 megapixels. So at some point your 12 MP image needs to be turned into 77 MP and the only question is where that happens. I tend to use Loxley for printing and their printers handle the upsizing; I just upload a 12 MP image and they do the rest. It just sounds like your printers want you to do the upsizing instead of them doing it.

Personally I think that's a bit odd, because it would mean you'd have to create and upload a separate image for each different print size. Surely it would make more sense if you just uploaded a 12 MP image and then their printer could resize it for 36x24, or 24x16, or whatever you(r clients) want? But if they really don't work like that, then they really don't work like that.

 

[Pegasus_Thrust]

Cheers Stewart. I am coming to a similar conclusion re: having to upload a special version for a specific size. What also has thrown me is that if I go directly to the vendors I reckon they will print it and handle the upsize at their end, I think that it is only when the order is being processed via zenfolio that the dpi resolution is flagged.

For my own peace of mind then, if my photo is essentially made up of 12,000,000 little pixels that together show the image how does it add a further 55,000,000?...... I take it that the additional pixels don't improve the quality per say but merely just divide the image up a whole lot more?

I'd love to see the difference between a 12mp picture printed at 36 x24 and then a 12mp adjusted so it is a 77mp picture printed at 36 x 24...........by my logic there would be little difference.

 

[bass_junkie83]

I have made the mistake of sending a wrong sized file to ovi once before and got a lovely pixilated mess back. Them not resizing is their only real downside imo.

I know you are using zenfolio, that means you need to upload a file suitable for your biggest size offering which can be a real pain when it comes to uploading a large set!

My workaround is to upload 'regular' sized files to zenfolio and offer auto fulfilled products up to that maximum size. Larger sizes I have set as self fulfilled products and go through ovi directly with the required file size myself. A bit of a pain, but for me I don't sell much large prints so the saving in upload times is worth it.

 

[StewartR]

I'd love to see the difference between a 12mp picture printed at 36 x24 and then a 12mp adjusted so it is a 77mp picture printed at 36 x 24...........by my logic there would be little difference.

I'm not sure what you mean. Most printers work at about 300 PPI so the image has to be adjusted to 77 MP as part of the process. The only difference is where it's adjusted and by whom. As you rightly observed, the adjustment process can't create any extra detail.

Here's a thought experiment. You have a 300 PPI printer and a 118 PPI printer. You upscale your 12 MP image to 77 MP and print it at 300 PPI, and you print it without upscaling at 118 PPI. There won't be any noticeable difference between the two prints.

 

[Pegasus_Thrust]

Thanks everyone and I think your workaround Dave is the way forward with this. It's a bit of a ball-ache become you'd like it to be a little more automated but that's life I guess.

Stuart that's sort of what I thought, I'm guessing the ppi resolution is to suit the configuration of the printer more so than improve the resolution to enable to become big enough.

 

[Chappers]

Stuart

In my experience I have always tended to leave any size adjustment to the printer. Most software has good interpolation algorithms so up sizing isn't normally a problem ( within reason). I've had some excellent images printed up to 36"from a 6 MP camera. All I did was send the file ( JPEG, 100% quality ) and the results came back stunning. Only thing I found out was not to over sharpen, as printers usually put a dose of sharpening in by default. 48" prints from a 21 MP camera are a piece of cake

John C

 

[john_e]

I recently sent some 16x12s to DSCL and needed them upscaling, I took the same shot and resized one copy in Perfect Resize 7.5 and left the printer to upsize the other. The resized print was of noticeably better IQ than the one which was left at its native size (I'll dig out the exact dimensions later).

 

[Ozei]

I recently sent some 16x12s to DSCL and needed them upscaling, I took the same shot and resized one copy in Perfect Resize 7.5 and left the printer to upsize the other. The resized print was of noticeably better IQ than the one which was left at its native size (I'll dig out the exact dimensions later).

Perfect Resize is pretty impressive - DSCL probably used something less effective (e.g. Photoshop's Image menu > Image Size).

 

[Sko77y]

Thanks for clearing that up, interesting read. Does anyone know if Bonusprint resize prints? I've only just tried loxley and they are very good.

If they resize, I'd be inclined to go back to them. the A3 print I got was excellent. Wish I'd known before I got a canvas from Bonusprint!