Photo sizing

[Trix]

I'm currently trying to get my head around photo ratios etc and was wondering if anyone knows a good online tutorial about it?

I use photoshop elements and when I crop I use the 6 x 4 crop but i'm not sure what sizes I can enlarge to before the lab will crop parts themselves. Should I be cropping in a different size? I also save them at 300ppi if that helps

Any help would be greatly appreciated.

[I @ M]

Trix, with limited exceptions the "native" format of a dslr camera is a 2:3 ratio eg;
4x6
6x9
8x12
12x18 print sizes and so forth.

If you crop anything from any print you will lose pixels and reduce the quality of the resulting print. That loss may not even be noticeable at a very small print size but it will show up as you get to larger size prints.

If you crop a photo to a non native size eg. 8x10 most commercial printers simply print that to the corresponding width paper.

If you crop to really really odd dimensions most commercial printers will simply print it on the paper that closes matches the width of your image and leave a plain paper border for you to trim later.

When we send our photos down the telephone line to our printers we always simply leave it at 300dpi and avoid cropping any larger sizes to reatain better quality in large prints.

For images that we send cropped at 8x10 for example we simply crop at that ratio in the software and send the image as is.

I hope this is some way clear, if you are confused or need more info, post away, someone might well be able to explain it better than me.

[Trix]

Thanks Andrew for taking the time to reply.
I think i'm going to have to get some printed to see the different results with sizes.

Say I have saved my image as 6x4, if I took it to a printing place and wanted to have bigger sizes done, which sizes could I print at without them cutting heads off etc? I understand that image quality can become less as enlarged but was just wondering about the sizes.
Sorry if these seem like silly questions...

[ricktas]

You need to use equal increases (multipliers) to ensure no cropping of your photo

So for your example of 6x4, you could print at 12x8 (6x2=12 and 4x2=8), as long as you use the same multiplier your photo will not be cropped, so using 3...6x3=18 and 4x3=12, so you 6x4 could be upsized to 18x12.

Hope that makes sense.

[Trix]

Thanks Rick, that definitely helps!

[I @ M]

Trix, I don't see any need to resize your photos in the first place.
Just leave them as they are on the pc ####pixels x ####pixels and let the printer's software do the resizing if they are in the native 2:3 ratio.
If you crop them to an 8x10 (out of native ratio), do it at the full size and once again let the printer's software do the sizing.

Am I making sense?

[Trix]

I don't resize the photos (i dont think i do anyway). When I load them into elements and want to crop a photo, I have to select an option for aspect ratio. The options it gives me are no restriction, use photo ratio, 2.5x2, 3x5, 4x6, 5x5, 5x7, 8x10. I have been using 4x6. I have never actually gone into resizing.

[I @ M]

OK, if you are using the 4x6 ratio consistently no further cropping will result when printed so you won't lose "heads" if the image is printed larger.
The only thing that will happen is that as you print larger and larger from a cropped photo the image quality will deteriorate faster depending on how much of an initial crop was done.

[Trix]

Oh wow, i didn't realise that the more you crop, the faster the iq deteriorates as you enlarge it. Thanks for that! I guess I need to make sure I don't go crop crazy. I take a lot of photos of kids so I always make sure I take the picture with plenty of space around the subject because they move so much lol

[ricktas]

Oh wow, i didn't realise that the more you crop, the faster the iq deteriorates as you enlarge it. Thanks for that! I guess I need to make sure I don't go crop crazy. I take a lot of photos of kids so I always make sure I take the picture with plenty of space around the subject because they move so much lol

Open your photo in your editing software and zoom in, now zoom in again, and again and again. There comes a point where your photo looks pixelated and probably the subject is not recognisable. This same effect occurs as you print larger and larger.

So taking this in mind, if you have cropped your photo and made it smaller to start with, as you enlarge it, you are going to hit that pixelated point sooner.

[Trix]

Thanks Rick, I have done that before just to see how far I can go before it becomes pixelated.

[aycee]

Gday Trix
On resizing if instead of cropping use the image size tool and untick resample image and put in the dimensions you need and everything will adjust by being linked....you lose no pixels...for example if i have a photo that is 18 inches by 12 inches at 300 ppi and you type in 6 by 4 in the dialogue box for dimensions you ppi will increase rapidly and no pixels will be lost, no data will be lost and no image quality lost in fact some say it gives better image quality

just make sure you dont have resample image ticked..you will have to get very sophisticated programs such as the CIA or NASA uses to enhance images and make them larger by resampling..ie Google Earth Photoshop doesnt cut the mustard so to speak

the same works the other way ...if you increase the dimensions the ppi will decrease and with todays labs and good printers you can easily go down to 200 ppi and even 150 ppi without any noticeable affects...300ppi was the standard when i was a boy and printers arent what they were..they are really good in comparison

all this is for printing only coz you want really best you can get from the image....

cropping is a different matter as it can easily ruin the pixel numbers and lose quality and would be for me a last resort..if you must crop an image so it actually gets bigger either dont put a ppi figure in the box or and use image size afterwards or put in 200 ppi if you have a 300ppi image and suck it and see

hope this helps as theres is so much jargon around about image size and cropping etc..and this missive of mine is part of it...more grist to the mill

regards Alan!

[Trix]

Sorry I havent replied sooner, I have been having issues with my internet provider....

Aycee - I go into image size and I can see that I can change it to 8 x 12 but I can't edit both height and width so I can change it to 8 x 10. If I want to change an original 6 x 4 image to 8 x10, what is the best way to go without losing too much image quality?

[aycee]

Re the image size vs quality..i think it might be easier to think of the amount of pixels...each pixel is one colour only and it depends on the number of pixels per inch for the quality of the variations in colour so the idea is not to lose any pixels rather to spread them or squash them..if the computer has to manufacture them quality will be lost..so if you have a 6 x 4 and want a 12 x 8 and do it in image resize without the resample image being ticked you can see if the ppi is too small and i wouldnt go below 150...thats really it...

hope that helps...Alan!