How do I make photos "life size" on my screen?

[rbiemer]

I think I must be missing something obvious but I can't seem to figure this out.
I've been digitally printing some photographs at 5"x7" and I want to do some work on them at that size.
I thought that if I re-sized the files to 5x7 and to the default resolution of my screen and if I then view the image at 100% it would show on my screen at the "real" size. But that's not working.
I hope I'm just making some basic mistake and you folks can help me figure this out.
Thanks for any help!
Rob

 

[vicmortelmans]

I don't think your software 'knows' how large 100% will be on the screen. Just imagine that you change your screen resolution setting from whatever it's now to 640 by 480 pixels... the displayed photo would become larger, just as the buttons and other GUI-elements on your screen.

My best guess is that 100% means that 1 pixel in your bitmap will be mapped to 1 pixel on your screen.

If the displaying application is a bit more sophisticated, it may also take into account the dpi (dots per inch) that's stored in the image metadata. You can measure the dpi of your monitor and store that in the image metadata and see if this changes the way the image is displayed.

Otherwise, you'll have to do some more involved calculations to get it right.

Groeten,

Vic

 

[oscroft]

I don't think your software 'knows' how large 100% will be on the screen. Just imagine that you change your screen resolution setting from whatever it's now to 640 by 480 pixels... the displayed photo would become larger, just as the buttons and other GUI-elements on your screen

And even if it can know the resolution of the screen, it has no way of knowing how big that is in inches - I have two different monitors that I can set to the same resolution, for example, and one is much bigger in inches than the other.

 

[rbiemer]

So, the simple thing I was misunderstanding is that this was not such a bright idea!😀
A close approximation will work for me and I'll stop sweating this. Thanks!
Rob

 

[MadMan2k]

The screen is usually 72dpi, and a 5x7 print from a 4000px scan would be over 500dpi, so if you scale the picture to 5x7 at 72dpi, it'll be much smaller in actual pixels (500px), which will work fine for viewing it on your screen but when you get the print you won't get as much detail. I try to keep the file as big as possible even for 5x7 prints, which you don't really need to do, but you will want it bigger than 500px so you'll have to just set it to quarter or half size in photoshop or whatever to work on it.