Editing in Photoshop from Lightroom

In the past (more than 6 months ago) I used to perform my initial edits in LR, export as .jpeg (no resizing), then open in Photoshop for additional editing as needed (e.g. retouching).

I've recently started doing some compositing and have started to utilize the Edit In Photoshop command, rather than exporting. I found it nice that I could just save the image in Ps, and it would automatically re-import back into Lr. Tonight, while working on a project I decided that I wanted to check and see what the image dimensions were (specifically ppi) and found it to be 300ppi... I found this odd since I knew that I had cropped the original image a bit - and it's usually never a 'clean' number.

I went on to check the preference in Lightroom for External Editing and realized there was a setting for the output resolution (which is apparently how the file is sent to Ps). I wanted to leave the field blank and have Lr send the native pixels (for lack of a better term) to Ps, but found that it has to be set to a value between 72 and 600. Am I correct to assume that Lr will resample the image to whatever this value is every time I use the Edit In command?

Can someone explain why anyone would want this? Is there a better way? What am I missing?

Nevermind. Pixel dimensions are the same regardless of resolution setting.... I thought the images were being resampled first.

Ppi is not an image dimension.

It can be any number, clean, soiled or filthy.

That ppi number is just a tag with an imaginary number. Ppi means "pixels per inch". How many inches does a digital file have? None, so ppi only becomes a real number when a print is made. Ppi has no effect on the way an image is displayed on a screen, because it is always displayed at that screen's resolution. If it is an application that supports zooming the image, it is still at the screen ppi but the ratio of image pixels to screen pixels changes.

Until it's print time there is no relation between pixel dimensions and the ppi tag. You could have a 100 million pixels and 10 ppi or a hundred pixels at 1,000 ppi. Because ppi is meaningless it can't, in itself, affect pixel dimensions. Some applications may change the ppi tag by default or because you have set it to do so, but the new tag will be just as meaningless.

Any application can only resample the image if you give it a reason to, i.e. specify a print size and the ppi for that print. Then it will add or remove pixels to reach the number of pixels that will cover the print at the target ppi density.

Like Elie says, the ppi tag is meaningless. The people who first decided the exif standard deemed that it had to hold some non-zero value, because some stupid software would calculate the image size, in inches, by dividing the size in pixels by the ppi value - and dying horribly when it tried to divide by zero. At the time (several centuries ago) 72dpi was the resolution of a monitor on a computer made by some little company that was popular amongst the graphics-guru hippies of the day. So the exif standard (written by those same hippies) said that the default ppi value should be 72.

tzalman wrote in post #15945869
Ppi is not an image dimension.

It can be any number, clean, soiled or filthy.

That ppi number is just a tag with an imaginary number. Ppi means "pixels per inch". How many inches does a digital file have? None, so ppi only becomes a real number when a print is made. Ppi has no effect on the way an image is displayed on a screen, because it is always displayed at that screen's resolution. If it is an application that supports zooming the image, it is still at the screen ppi but the ratio of image pixels to screen pixels changes.

Until it's print time there is no relation between pixel dimensions and the ppi tag. You could have a 100 million pixels and 10 ppi or a hundred pixels at 1,000 ppi. Because ppi is meaningless it can't, in itself, affect pixel dimensions. Some applications may change the ppi tag by default or because you have set it to do so, but the new tag will be just as meaningless.

Any application can only resample the image if you give it a reason to, i.e. specify a print size and the ppi for that print. Then it will add or remove pixels to reach the number of pixels that will cover the print at the target ppi density.

Completely understand... but the end result of my editing will be a print, not a just digital file. I plan to print this specific image as an 11x14 and was hoping that my resolution was above 200 (preferably 250 or above) for the given print size.

I'd much prefer that the file contain 250ppi vs. adding the difference during the printing process.

drvnbysound wrote in post #15946332
Completely understand...

Seems like you don't…

drvnbysound wrote in post #15946332
but the end result of my editing will be a print, not a just digital file. I plan to print this specific image as an 11x14 and was hoping that my resolution was above 200 (preferably 250 or above) for the given print size.

I'd much prefer that the file contain 250ppi vs. adding the difference during the printing process.

A digital file only has one thing: A dimension in pixels.
You get a size by (arbitrary) choosing a ppi and vice versa.

If you want a 11x14" file at 200ppi or more, you will need a file that's 2200x2800 or more pixels. Doesn't matter one bit whether the "ppi metadata" in the file is 1 pp1 or 1.000.000 ppi…

You can quickly check your print resolution in Photoshop using the Image/Image Size dialog.

To check its "native" resolution for a particular print size, uncheck the Resample Image option and leave the Constrain Proportions option checked, and then enter a width or height in inches in the dialog. When you do this the other dimension will be automatically filled in and the Resolution/PPI value will be filled in for that print size.

You can resize the image to a given resolution for a given print size by leaving the Resample Image option checked, and filling in the dimensions (make sure the image is cropped to your desired aspect ratio). This may or may not have noticeable benefits, depending for one thing on the efficacy of your print driver in automatically resizing a photo for printing. I've gotten good results (good, crisp fine detail) from printing images with less than 200 ppi "native" resolution. However, an advantage of resizing an image is that you can do more processing, such as output sharpening, on the image using the "final resolution".