A3 and A4 Prints

Hello everyone

I want to crop my image into three seperate images and then order either A3 or A4 prints online for each section, so when on the wall three images will make up one large image.

My problem is that when I do this the individual images are to small either height or width for the sizes I require.

 

Any idea what the total image size of the original image should be before cropping?

 

I did find somewhere that said A3/A4 prints should be a minimum of 2480 x 3508 but that would mean my original image would have to be a total size of 7440 x 3508 which is way larger than I have.

 

Any suggestions for a possible solution please?

Thanks.

Those dimensions you give are if the image is printed at about 200 PPI. Three A3 printed at 100 PPI would need a 1658 x 3510 pixels image. That is about a 1:2 ratio. Most cameras take 2:3 or 4:5 ratios. Just what size image are you starting out with? If it is not a 1:2 ration you are going to have to crop out a lot of the original image to make it fit.

I've seen mural-sized images printed from a little 8 or 10 megapixel compact digital camera. They looked great from a 'normal' viewing distance.

 

If the image is strong enough to start with, it'll stand almost any degree of enlargement.

 

You can always increase the pixel size by interpolation, and there are even some clever 'AI' programs that artificially create more detail.

 

See this thread.

 

Straightforward interpolation or up-sizing doesn't add any real detail, but a little judicious sharpening after up-sizing can make the image more than acceptable as long as nobody sticks their nose against the final print to scrutinise it.

If the lab you are using is worth a salt and these are RA4 based digital prints (most are) then there's no need to upsize. All those printers have excellent RIPs that upscale seamlessly as long as you have a tack sharp file devoid of artifacts. 100dpi is no problem for a big print or mural provided again it's a good file. I do it all the time.

 

For inkjet printing dpi is another story, but most of those fine art printers will warn you about dpi ahead of time.

Paper size A0 is one square meter in area, with the sides in the ratio of 1 to (square root of 2) - i.e. 1:1.414...This gives 841mm x 1189mm

A1 is half this area in the same proportions. The ratio (half the sq root of 2) to 1 is equal to the ratio of 1 to (sq root of 2). And so on. You just halve the long edge each time.

James above said a ratio of 1:2, which is near enough (actually 1.414 vertically and 3 x 1 across gives a size ratio before printing of (3/1.414) or 1:2.12.

So yes, you will lose quite a bit of your image top and/or bottom to cropping.

But for a good sharp starting image you should be able to upscale by at least a factor of 2, as noted above, before you print.

So get a good image with sides in the ratio of 1:2.12, then divide into three equal slices for printing.

Larger prints tend to be viewed from farther away, which is why you don't need as much DPI (or, for A3, D/mm) as for smaller prints.

 

In days past, people used to make murals from 35mm negatives and slides.

 

Many enlargers have the ability to rotate the head 90 degrees, such that you can expose on a wall.

Somehow attach strips to the wall, expose the whole thing, remove and process the strips, then put them

back up on the wall again.

 

If you want a test, crop some image down and print an A4 from it. The look at it from near and far, to

see how it looks. Maybe put it on the wall, and step back while looking at it.

 

Note also that you said "should" along with the 2480 x 3508. I agree that you should, but not that

you must. You can get away with a little less, especially if you will view from farther away.

 

Some printers that I know, will warn you that the resolution is low, and then even lower,

refuse to print it.

Glen mentioned a really good tip before spending money on a big enlargement, and that's doing a crop test. I do the same before making a large print and want to make sure I'm not upscaling too much. You spend $2-3 on a test 8x10 at the final size and DPI as your full mural will be and you can view exactly what the quality will be, Worth it in my book. Good tip Glen.