Lightroom - does not show image size in inches. Must go to PhotoShop. Unnecessary extra step.

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Lightroom - does not show image size in inches. Must go to PhotoShop. Unnecessary extra step.
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Donald Alschuler

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Posted 1 year ago

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Yves Crausaz

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Well no ... it's already the case in the export module, we can give him the sizes in metric system or US system, in the print module too, so for me, no more step in work modules, grid and development!

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Dan Hartford Photo

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Inches is not an attribute of a digital image.  A digital images can be viewed or printed at any size.  The only true measurement of a digital image is the pixel dimensions.   

Only if you add in the idea of DPI (dots per inch) for your output device can inches be derived and the DPI can be different depending on printer and/or display device.  

What do you need the Inches measurements for?   If for printing then the print module gives you all of that.
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Johan Elzenga, Champion

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Exactly. An image in Lightroom does not have a dimension in inches, that is why Lightroom can’t show it either. Only when you define the image for a certain output, like a printer, you can add PPI (not DPI) information, where PPI stands for pixels per inch. That means that you can define inches in the print module, and when you export an image you include a PPI value in the exported image.
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Donald Alschuler

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Thank you for all your replies. You have confirmed the limitations of Lightroom. I order my prints on line and need to prepare them for the size print I want. That needs to be in inches.
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Laura Shoe, Champion

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Hi Donald, there's no need to go to Photoshop to size files to send out to print - you can prepare them for the size print you want, exactly as you say, in the Export dialog. In the Image Sizing section, check Resize to Fit, then from the dropdown choose Width and Height, Dimensions or Long Edge, choose inches instead of pixels, type in the appropriate numbers and set your print resolution:



Note that if you're specifying Width and Height or Dimensions and you want your image to be exactly that size, it first needs to be those exact proportions - which means you'll need to crop to those proportions in the Develop module before export. 

Before printing it can be helpful to see how much your image will need to be enlarged to reach your desired print size. You can examine native photo resolution in Lightroom's Print module and compare it to your print resolution. See this article I wrote, "How Large Can I Print This Photo? Understanding, Managing and Displaying Print Resolution in Lightroom."  
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Dan Hartford Photo

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BTW, adding on to what Laura said, in order for this to produce the exact dimensions you desire you will have to know the number of Pixels Per Inch (PPI) of the printer that will be used to print the image at the lab.  

Also, what online lab do you use that requires YOU to provide the exact number of pixels?  All the labs I've used allow me to select my print size and they will let me know if I have too few pixels.   

Also any lab worth it's salt will do an excellent job at down sizing images that have too many pixels for their printer to handle so just going with your full compliment of pixels is not a problem. 

However, having said that, when I want to be anal, I will do what Laura suggests and set my image size in inches in the export dialog along with the PPI value for the printer the lab will use for that image size and paper type.  But, will also do a rough calculation (long edge pixel count divided by PPI) to assure that I'm in the ball park of how big a print my number of pixels will support.  For  example 3000 pixels on a 300 PPI printer winds up being a 10" print.

I know many will argue with this, but in general I find that I can usually print double the number of pixels I actually have available and still have a quality image.   For example if my image is 3000 pixels wide and the printer is 300 PPI I would not hesitate to make a 20" wide print.  In these cases I usually let the lab do the up-scaling.   That's what quality labs do for a living.  If I need to go higher than double my pixel count, I'll upscale myself using Photoshop or other software designed for that purpose
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Laura Shoe, Champion

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While I think we're off track of what the OP asked for, I personally wouldn't, under most circumstances, use this rule of thumb of Dan's of doubling the long edge of the print beyond what one would get calculating PPI at 300. This reduces the native photo resolution from 300 to 150 PPI (3000 pixels/20" print).  Compared to the 10" print, this requires, not doubling the number of pixels, but instead at least quadrupling the number of pixels  (since we're working in two dimensions)  - so 1/4 of the photo pixels are real, and 3/4 are invented by LR or PS. Tests I've done with my images and this much interpolation show a serious loss of quality. That said, I haven't tested with Photoshop's newer Preserve Details method.
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Johan Elzenga, Champion

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Quite frankly, I think the OP gives this way too much thought. If you send an image to an online printer, and you order a certain print size in inches, then that is what you will get. The only thing that is important is that you do not send a too small file (in pixels). As long as the file size meets or exceeds the specifications, you will be fine.

Try it yourself. Send two copies of the same photo to an online printer, one file at 3000x4500 pixels (10 x 15 inch @ 300 ppi) and the other file at 4000 x 6000 pixels (10 x 15 inch @ 400 ppi). Order a 10 x 15 inch print for both. Try to spot the difference when they come back.