Resizing / Printing Images Question

Thanks for all the replies.
I'm going to have to spend a little time trying to understand the more detailed ones a bit better.

In my initial post I said that I used Photoshop to resize the images which I did because that's what I had used in the past before I started using Lightroom a lot more.
When I noticed that I couldn't change the resolution from 72px/in to 300 px/in Photoshop (I'm sure there's probably is a way to do that) that's when I tried to do things in Lightroom.

I've figured out.. I think.. what I was doing wrong in Lightroom.
I knew that I should've been able to bring back up the original RAW file in Lightroom to make further size/resolution adjustments for printing purposes but, I couldn't find the original RAW file in the library film strip.
Either I was doing something wrong or Lightroom was experiencing a glitch at the time.
I closed out and then reopened Lightroom and then I was able to see the RAW files in the library film strip containing the prior develope mode adjustments.
I was then able to make the size/resolution adjustments in develope mode for printing that I wanted to make.

The reason why I asked if I should change the resolution from 72 to 300 is because anything I've seen or read suggest that for printing purposes, the resolution should be 300.
Does that actually make a difference, I have no idea.
I had the resolution at 72 for emailing purposes.
Any pictures I sent via email were for viewing.
The recipient had no plans of printing off the pictures.

From some of the replies, it appears that my cropping process isn't being done right?
When I get an image in Lightroom that I'm going to crop, I just crop it to how I like it.
I've never set the cropping tool to specific pixels. That's something I'll have to look into.

Getting the pictures printed off today so, should be interesting to see how they turn out with the Lightroom size/resolution adjustments.

The main time I worry about DPI is printing. If you go to image size dialogue, you can see what changing DPI with resampling does (it tries to make more pixels and increase resolution/print size when you increase DPI). If you have it unchecked, you can adjust one property (like width or DPI) and then see how other properties are changed (it’s not adding or subtracting pixels). 72 DPI has been an old standard from the old CGA/VGA/Mac classic days...now with so many different resolution and sized monitors, it’s becoming more moot. When working in production, my general rule of thumb for print is 300DPI if it’s a print that’s going to be seen closely. If it’s a poster, chances are viewing distances aren’t as great and I’ll tolerate 120DPI. Billboards can have really low DPI since they’re only viewed from afar.

john crossley wrote in post #18689313
Now export the same image from Lightroom twice. The first at 300ppi and the second at 72ppi open them both in photoshop and view at 100%.

OK. Here are the first two. There will be 2 more posts to follow with the same images.

These were resized to 1024 on the long size exported at 0 PP1 and 1000 PPI. First one is 0.

These two were exported without resizing at 72 and 300, zoomed to 100%, cropped and even the PPI size is showing.

These two were exported without resizing at 1 and 1000, zoomed to 100%, cropped

So perhaps when you download my images it defaults to 300. Like Wilt said maybe something to do with the EXIF. On my system it retained the PPI size for each. I see no difference between 1, 72, 300 and 1000 PPI at 100%.

Here are the original ducking resized images.

john crossley wrote in post #18689313
Now export the same image from Lightroom twice. The first at 300ppi and the second at 72ppi open them both in photoshop and view at 100%.

DONE in post 27 images

BTW, neither viewing on a monitor NOR viewing on a inkjet print have any perceptible change in quality using 75 dpi file vs. 300 dpi JPG file as the source.

The below is the only thing important when uploading images or taking images to a store to be printed. Take the print size desired, multiple each dimension by 300 (as a general good rule to follow), and then make sure the circled area is enough to cover those numbers.

DPI means nothing. All images I have ever sent printing services and local printing show 72dpi in that setting, but the final image resolution was all that was needed to produce the desired prints.

davesrose wrote in post #18689336
The main time I worry about DPI is printing. If you go to image size dialogue, you can see what changing DPI with resampling does (it tries to make more pixels and increase resolution/print size when you increase DPI). If you have it unchecked, you can adjust one property (like width or DPI) and then see how other properties are changed (it’s not adding or subtracting pixels). 72 DPI has been an old standard from the old CGA/VGA/Mac classic days...now with so many different resolution and sized monitors, it’s becoming more moot. When working in production, my general rule of thumb for print is 300DPI if it’s a print that’s going to be seen closely. If it’s a poster, chances are viewing distances aren’t as great and I’ll tolerate 120DPI. Billboards can have really low DPI since they’re only viewed from afar.

The dialog box and the way the program behaves MIGHT change, but simply changing the dpi value does NOT change anything except the value embedded within Exif of the JPG.
I just demonstrated that point in my post 27 images...BOTH images have 2715 x 1810 pixels, created from the same 2715 x 1810 pixel crops of the full frame. One is output at 75 dpi, and the second one is output at 300 dpi. (Used LR 5.7 to output the two JPG from an image captured from a 7DII camera.)

TeamSpeed wrote in post #18689377
The below is the only thing important when uploading images or taking images to a store to be printed. Take the print size desired, multiple each dimension by 300 (as a general good rule to follow), and then make sure the circled area is enough to cover those numbers.

DPI means nothing. All images I have ever sent printing services and local printing show 72dpi in that setting, but the final image resolution was all that was needed to produce the desired prints.

Hosted photo: posted by TeamSpeed in
./showthread.php?p=186​89377&i=i202169754
forum: RAW, Post Processing & Printing

I know that. As requested I'm only illustrating that no matter what PPI you set it to will not make a difference for screen viewing. So in the end when you find a suitable PPI and both print and post images at POTN you don't have to switch between 300 and 72. You can leave it at 300 PPI for both. Of course if you are using two different type of printing methods - inkjet vs laser you may have to have a PPI value for both.

I just noticed the 72 PPI thing and thought I could save someone a step. If anyone wants to take the step to set it to 72 PPI to post here or email an image fine by me. There is no advantage to it.

Wilt wrote in post #18689378
The dialog box and the way the program behaves MIGHT change, but simply changing the dpi value does NOT change anything except the value embedded within Exif of the JPG.

Now do as what my quote says, and you’ll see that in PS, with resampling enabled, changing DPI ALSO changes size!

I know you know that. I was just using your screen grab to make the point to others. It was too convenient to not use as an example.

davesrose wrote in post #18689400
Now do as what my quote says, and you’ll see that in PS, with resampling enabled, changing DPI ALSO changes size!

1. LR is like Photoshop...when you use DPI value to drive the output, the end result is a different PIXEL COUNT (ppi) file.

   Output a 4x6" at 300 dpi results in 1200 x 1800 pixels in JPG
   Output a 8x10 at 300 dpi results in 2400 x 3000 pixels in JPG

2. But when you specify output as a PIXEL COUNT, changing the DPI value only results in the embedded Exif data having '75' vs. '300' with zero difference in the file actually output.
   

davesrose wrote in post #18689400
Now do as what my quote says, and you’ll see that in PS, with resampling enabled, changing DPI ALSO changes size!

There is the problem. PS is very inconsistent here. If you have that checked, and change Resolution, it then changes the pixel Width and Height. However if you change the Width and Height yourself, it doesn't change the Resolution. It is broken, IMO.

Never touch DPI, it is an unnecessary item to have in the PS resizing screen. That resampling is only when you are changing the physical size of the image in overall resolution, different resampling settings employ different algorithms when it either manufactures pixels or reduces pixels.

Wilt wrote in post #18689408

But when you specify output as a PIXEL COUNT, changing the DPI value only results in the embedded Exif data having '75' vs. '300' with zero difference in the file actually output.

In PS's image size window, Resolution (Dot Pitch) does change

TeamSpeed wrote in post #18689409
There is the problem. PS is very inconsistent here. If you have that checked, and change Resolution, it then changes the pixel Width and Height. However if you change the Width and Height yourself, it doesn't change the Resolution. It is broken, IMO.

I don't view it as broken: it's that specific feature of changing a document's image size (just as the dialogue says). If you have resampling unchecked, Photoshop will give you the approximation of what DPI or size will be of current image size (and at least with my version of PS, Resolution does change). With it checked, you can chose what resampling method to use for resizing image size...whether it's resampling for increasing DPI or stretching a dimension. Having to work both with generated graphics and photographs, PS's image size window makes sense for my applications (where on top of resizing images, I create new PSD files for video presentation or print).