resizing and resolution

[zbgump]

I have a basic question that I should know the answer to. I'm working some pics my friends took with their digi cam to be sent to shutterfly. These images are being shrunked down by quite a bit.

My questions is, is their any gain or loss by increasing the resolution when I decrease the size?

The reason I'm wondering is that shutterfly.com puts some resolution restictions on what they'll print for different sizes. I guesss they don't want anybody complaining about low quality prints.

Thanks in advance for any advice.

[roger_ele]

A 4x5 image at 150 ppi is the same exact image as an 8x10 image at 75 ppi. Test it out, create a new 8x10 image at 75 ppi in photoshop, go to 100% view, go to Image>Image Size and change your ppi to 150 with resample turned off - it will change to 4x5 deminsions, click OK - and also notice that the size of the image in photoshop that still says 100% hasn't changed. It is just the difference between how many physical inches you spread the same pixels across (ppi = pixels per inch)

If they have a minimum and a maximum the minimum would be for quality purposes, the maximum would be so they don't use up storage space on their hard drives and slow down the printing with larger than necessary image files.

In terms of doing the photos for your friends; if you want them to be the best quality, do your art work or enhancement at the current image file size, save it, make a copy and resample the copy down to the image size and resolution (ppi) that shutterfly requests. You will then have a master copy at the higher resolution (more information = bigger file size = more detail in your image), that you can use if you ever want to make a larger print than you had shutterfly make for you. If you try to enlarge a smaller file size image phtotoshop guesses what pixels to create - you don't gain detail.

Hope this helps, Roger

[Stephen M]

A link to further links on the subject of Resolution and resampling:

http://members.ozemail.com.au/~binaryfx/PSTV_links.html#R

Hope this helps,

Stephen Marsh.