Why do I get jagged-edged photos when I shrink my jpegs?

Question

I'm taking 7.1 mp pics with my camera, and when I resize my image on my computer to shrink it, it gets these jagged edges... why?

Answer 1

The technique you are using to resize is resulting in pics that are too low resolution. This will give you zagged edges when you print.

Many cameras use 72 pixels per inch (ppi) as the default pixel density when they create the picture image file. They could set it to anything, but use 72 based on the historical density of old crt's.

So your image size will show as a too large width and height, and a too small ppi.

If you resize to a smaller width and height, and keep the resolution at 72 ppi, the software will throw away most of your 7.1 million pixels and leave you with the jaggies. 72 ppi is way too small for good prints.

If you do not check Resample, the software will keep all your pixels and you will not have jaggies.

If you want to reduce file size, use Resample but type in a resolution not less than 300 ppi. This will throw away some pixels, but also give you good prints.

I never throw away pixels unless I know that the pic is only for a one time use. I want my keepers to stay as good as they came from the camera. All it costs is hard drive space.

Good Luck

Answer 2

It has to do with the processing of the image and also the interpollation when resizing.
In my experience the key is resizing by percentages. I recommend using 25%, 50%, etc. Some percentages occasionally will leave these sharp edges behind also.
I've seen situations where a 1 megapixel camera provided 'higher quality' images resized versus a 7 megapixel camera. In reality the 7 megapixel camera provided higher quality images, but the 1 megapixel images where closer to the resized image so the image came out better.
This is a common problem when resizing images, and it can be quite confusing to find a way to resize that works with all images and provides better images.

Answer 3

If you are resizing them you have to calculate the resizing proportionately. Meaning the height has to be resized the same percentage as the width. If you are just resizing the photo say like in dreamweaver or displaying it on a website without actually resizing the photo in a photo software it will do what you are experiencing.

Answer 4

when you shrink the pictures it gets reduced in the pixel rating thus quality is also reduced