Image resizing and resolution question

[groovigyrl]

Hi, I hope someone can explain why the resolution increases when I crop down, rather than increases.

My document size is aprox 12X18 and the resolution of the image is 240 when exported from Lightroom. Pixel dimensions are - width-4288 and height-2848. When I crop to an 8X12 the resolution increases after the crop. I don't understand. Usually when you crop down, doesn't the resolution usually decrease? Now the resolution is up to 322, pixel dimensions are decreased to width-3866 and height-2577 (which makes sense). Can someone explain why the resolution increases? When preparing for print, the pixel dimensions are more important than the resolution number, right?

I'm cropping my images for 4x6 prints and am told to go with the largest dimensions and highest quality, this is why I'm croping at 8X12. Please correct me if I'm wrong. I have hundreds of images to edit from a Bat Mitzvah and I don't want to do this incorrectly! Thanks so much for any help!!

jane

[Heretic]

do you have resample image clicked on or off?

[groovigyrl]

It's clicked on. Thanks!

[mistermonday]

If you have cropped your 4288 x 2848 image down to 3866 x 2577 the resulting image at 240 dpi will be 16.117 x 10.733 inches. The only way you can end up with an 8 x 12 at 322 dpi is if you resized the 3866 x 2577 with the Resample Image box UNchecked.
Standard print resolution is 300 dpi so if you are downsizing a version to send out for 4x6" prints, you should resize to 4x6 x 300 checking the resample image box. BUT I recommend you you save the 4x6 as a copy so that you maintain all of the orig pixels in your master copy unless of course you are keeping you original camera NEF or Jpg for permanent archive.
BTW, the is no pint keeping all 12 megapixels (or 10M px cropped) in the 4x6 file you send to be printed because all the processor will do is downsize it anyway.
Regards, Murray

[groovigyrl]

Thanks for responding Murray. I didn't crop at all when in Lightroom. It automatically downsized pixels when I exported it into Photoshop. I find that to be very strange, since I'm used to 300 dpi. What's that all about? I was told to crop the larger the better. 8X12 is almost the same dimension as a 4X6 so that's how I've been cropping for 4X6 prints. Is this incorrect? It doesn't matter when going to print? The resample image box is always checked. I save everything in TIFF and copy to JPG when getting ready for print.

I'm still a bit confused. I'm not sure what's going on. More confused now because it's exporting with less dpi. Hmmm.

Thanks for your help. I appreciate it!

jane

[mistermonday]

Jane, I don't use Lightroom so I can not comment on why that transformation is occurring. Why don't you just crop and / or resize the image after you open in PS?
Regards, Murray

[groovigyrl]

Hi Murray,

That's what I do. I don't touch the image size until I'm finished editing in PS so this is a mystery. I suppose I'll join a LR forum and ask. Thanks again!

jane

[mistermonday]

Jane, if you image produced by the camera is 4288 x 2848 pixels (sounds like a Nikon 12M DSLR), then when the image makes it into PS, the number of pixels should be 4288 x 2848 NOT 3866 x 2577. Somewhere it is being cropped. If you are cropping it in PS, then Lightroom has nothing to do with your problem - it has to be something you are doing in PS.
Regards, Murray

[groovigyrl]

Thanks! Yes, I have a Nikon D90. Well, I exported an unedited image and the dpi was 240 when opened in PS. The dimensions of the example I gave in my initial post was for a 12X8 cropped in (downsized from the orig). This time, I cropped the same exact size (without cropping in) and the pixels remained the same (yay) but the dpi went up and is now 329. So...I'm stumped. I don't understand why the dpi is imported at 240 and goes up when I crop. Eh!

[mistermonday]

How are you cropping in PS? Are you using the Crop Tool or are you selecting with the Marquee and then Image>Crop?

[groovigyrl]

I'm using the crop tool to ensure that it is the exact size that I want.

[mistermonday]

When using the crop tool, are you entering the width, height, and resolution, or just the w & h?

[groovigyrl]

Just the width and height. Wow, I never thought to enter a dpi number! Isn't that adding pixels that aren't really there if I keep cropping down?

[mistermonday]

If you do not enter a resolution, PS will try not to discard any pixels. So if your new size is smaller than the existing size, PS will just redistribute your pixels which is why a 16.1 x 10.7 @ 240 dpi will become a 8 x 12 x 322 dpi. So always enter your resolution.
Time for me to get a few hrs of shut eye.
Regards, Murray

[groovigyrl]

Thanks so very much!! I'll be sure to do that from now on!! You've been extremely helpful!! I really appreciate it! Time for me to hit the hay as well!! Work in the am!

jane