Hammer Loc: London UK

Great stuff, many thanks .

Hammer Loc: London UK

Thanks for your help .

amfoto1 Loc: San Jose, Calif. USA

When I make "proofs" from Lightroom, I usually make them 700 to 800 pixels "on the long side". That's more than enough resolution for online sharing, but small enough that prints can't be made from my images without permission.

Using the "long side" dimension works well with almost any of the more standard aspect ratios or crops.... 3:2, 5:4, 7:5, etc. The only time I change this is when I make a 16:9 or panorama, which require a longer "long side".

I don't consider images converted and exported directly into a usable file type by Lightroom to be "finished". For higher uses, such as prints or larger digital usage, I always pass the image off from Lightroom to Photoshop for additional finish work. LR is great for what it is, but can only do so much. Or, another way of looking at it, PS can do so much more, with greater selection and control.

When I pass images off from LR to PS, that simply sends the entire file, cropped but without any resizing, over to PS (as a 16 bit TIFF). I do the final sizing there. For online usage I use 100 ppi. For most printing processes, I used 300 ppi. Both these are slightly more than what's needed.... I think 96 ppi is sufficient for most online display and many print processes call for 170 to 240 ppi... But by using 100 and 300 ppi the math is quick and easy and it rarely hurts to have slightly higher resolution.

For example, if an images is going to be used to make a 5x7 print, I know it needs to be 1500x2100 pixels (5x300 and 7x300). Or an 8x10 print will need to be 2400x3000 pixels.

Similarly, for an image to display approx 5x7" on most peoples' computer monitors, it will need to be 500x700 pixels. (This assumes their monitor is set to it's native resolution and doesn't allow for some variations such as 4K... but you can't accommodate every possibility.)

Some other final steps, I also usually reduce the image from 16 bit to 8 bit, set the color space to sRGB and save as a high quality JPEG. Those are necessary for online display and are what's required by many printers. (I occasionally accommodate customer requests for other file types such as 16 bit TIFF or PSD in other color spaces... but these are typically only wanted and needed for some commercial purpose.)

abc1234 Loc: Elk Grove Village, Illinois

Alan, no need to resize for printing. Just crop and you are done. For any online viewing, resizing helps because smaller images load faster than larger ones. In most instances, people will not see a difference between then too, especially if they are on a phone or tablet.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

According to https://www.facebook.com/help/266520536764594?helpref=uf_permalink

The maximum sizes are 720, 960 or 2048 px, and 100 kb, and anything larger will be resampled and/or resized.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

You do realize that when you specify 96 ppi, 170 ppi or 240 ppi you are not changing anything about the file, especially the resolution. That is just a field in the metadata that does nothing but possibly remind you that you created an image that you'd like printed to a specific size. As I illustrated in my previous post above, a 3 ppi image is EXACTLY the same as a 1200 ppi image.

https://medialoot.com/blog/quick-tip-how-to-change-the-pixels-per-inch-of-an-image-in-photoshop/

The number of pixels required in an image is all about viewing distance - a 4x6 requires a higher ppi (ppi in the finised image) than a 24x36 which will presumably be viewed at a greater distance. So at 12", a 4x6 requires at least 300 ppi, or an image that is 1200 x 1800 pixels, while a 24x36, typically viewed at around 4 ft, would require 80 ppi for the perception of sharpness - or 1920 x 2880 pixels.

This is a great source, with some factual info on the limitations of human vision and what is actually required for perceiving sharpness and detail in a printed image.

http://www.photokaboom.com/photography/learn/printing/resolution/1_which_resolution_print_size_viewing_distance.htm

It's important to note that a large theater with Sony 4K UHD projection only projects an image that is 4096x2160 px, or 8.8 mp, and the screens average 20 to 50 ft wide. At 50 ft, the ppi is a little under 7 - and the images on the screen still look crisp and sharp from the center rows and beyond.