My head hurts...

[E equals MC2]

We know that digital camera images are 4:3 ratio and printing medium is at 3:2 ratio.

If I wanted to print the image without cropping it to suit the 3:2 ratio, but making it up by adding BLACK borders at height.. at what ratio would I add the black borders?

I hope I'm clear...

 

[Rudee]

My head hurts...

Quit using your teeth.

 

[Cattlegod]

print on black paper

 

[giantpinkbunnyhead]

I believe you would add 1/4 inch of black bar per 2 inches of height.

Say your printing medium is 3" wide by 2" high. to scale a 4:3 down to fit that, you'd reduce to 3:2.25, or 3" wide by 2.25" high. So 2.25 -2 leaves the 1/4 inch black bar as a difference. (per 2 inches).

 

[Skeeedunt]

Huh? That's width:height I assume? So like .0625*width worth of black on each side?

 

[SOSTrooper]

According to your description, the width of the digital picture is narrower than the width of the photo medium, assuming that the height of both medium stays the same. So in theory you would have to put black borders on the sides of the digital picture, not on top and bottom. If you expand the width to fit the 3:2 ratio of the photo medium, then you'll be cropping the top and bottom, which I assume not something you want in the first place.

The width of the 3:2 ratio of photo is 1.125 times wider than the 4:3 ratio of the digital pictures. So if you have a picture that is 800x600, you'll have to add 800x0.125=100 extra pixels to the sides of the digital pictures. Since you probably want borders on both sides rather than just one side, just add 50 pixels to the left and right of the digital pictures. It'll be the same math with all higher megapixel pictures assuming they're all in 4:3 ratio (1600x1200, etc).

I hope my math is right.