30x40 poster format

[mikecox]

Lightroom Version Number

Classic

Operating System

1. Windows 10

I have been asked to create a montage of images for a 30x40 poster. I was hoping to use the Print module to set it up but there doesn't appear to be any way to create a poster size template, even for a printer that prints that size paper. But the client wants to have Costo print the poster, so I would print to a file saved on a thumb drive. Will I have to switch to Ps to get a page that size?

 

[LouieSherwin]

Hi Mike,

Unless you want to upsize the image in Photoshop you should export the full sized image cropped to 3x4 aspect ratio and let the CostCo printer handle the rest. I belive that they use Epsons for all the wide format printing and the Epson drivers are pretty good at scaling the image up. However, if your actual image pixel dimensions are too small it may not be able to scale. You will need at least a 3000x4000 image to make a decent poster of this size. That will be 100 ppi in the final print. It won't look very sharp up close but from the normal viewing distance for a print of that size it should look good.

The CostCo print ordering site should provide guidelines on the required dimensions.

-louie

 

[mikecox]

Hi Mike,

Unless you want to upsize the image in Photoshop you should export the full sized image cropped to 3x4 aspect ratio and let the CostCo printer handle the rest.

Actually, my client wants me to scan 128 standard sized photos, process them and reduce them to 2x3, then arrange them on a 30x40 poster.

If I load all 128 images onto a flash drive and give it to my client will Cosco actually arrange them onto a poster and print it for him?

 

[Bernard]

Assuming I understand correctly what you want to achieve, you have to
. create a new document in PS in 3x4 aspect ratio, as Louie said 3000x4000 pixels would not give very good quality, so say 6000x8000 pixels
. arrange the 128 images into that document
. export it
. send it to Costco and ask for a 30 inches x 40 inches print
You don't need LR.

 

[clee01l]

CostCo is only going to accept a JPEG of a certain size. The resulting 30"X40" print will need the largest number of pixels that can fit into the CostCo maximum file size If that 6000X8000 pixel PS composite work, the plan to Resize/Compression Quality in PS to achieve the maximum file size that CostCo can take.

 

[mikecox]

you have to create a new document in PS in 3x4 aspect ratio, as Louie said 3000x4000 pixels would not give very good quality, so say 6000x8000 pixels

I opened a blank document in Ps and used Ctrl-Alt-L to put in the 30x40 dimensions, that I set to 300ppi; which is the highest value I've ever set in that field, and the value used for printing. Should I change that value?

If I add jpg images saved with that same resolution shouldn't that print OK?

You don't need LR.

I thought I would process them in Lr then export them as jpg files, sized to 2x3 at 300 ppi. Then import them back into Lr and "edit as layers" in Ps. From there I could arrange them.
Should I do it differently?

 

[Johan Elzenga]

Photoshop can load images as layers as well. You don’t need to do that via Lightroom. Use menu ‘File > Scripts > Load Files into Stack’.

 

[mikecox]

Photoshop can load images as layers as well. You don’t need to do that via Lightroom. Use menu ‘File > Scripts > Load Files into Stack’.

Thanks, I didn't know that.

But the reason I planned to start in Lr was so I could batch export the images at the reduced size, so I would have to size them in Ps, one at a time; or is there a way to resize a group in Ps?

But using your suggestion I wouldn' t have to import them back in into Ls, I could just bring the exported versions in directly.

 

[Johan Elzenga]

Batch export from Lightroom at a reduced size makes sense. You can batch resize in Photoshop as well, using the Image Processor, but doing it from Lightroom is probably easier. Just don't import them again only to send them to Photoshop. That does not make sense.

 

[Bernard]

OK, I try to summarize :
You scan your 128 images in 2x3 ratio.
How do you arrange them in the 30x40 document ? Assuming the document is vertical, that's 8 columns x 16 rows = 128
Can you print directly from LR ? You can define a 30"x40" paper no problem, but the maximum contact sheet you can define is 8x15=120,
so it does not work.
You have to batch send them to PS at the correct size 500x750 pixels for a 6000x8000 pixels document.
How to arrange them in the document ? I am not a PS expert, I guess you have to define a grid with some clever option ?
And then save the document as tiff.
Convert the tiff to jpg with max quality and compare with max allowed by the print shop.
If it's too big, convert again with reduced quality until it's OK
Bernard