Reducing size and increasing resolution.

[johnnyguitar]

Hi folks
I know this is one of those questions that comes up time and again and I'd just like to go through it in words of one syllable that I might have a chance understanding.

I have been given some images of my band that I want to use on my website. These have all been supplied as 72dpi images - fine for on screen use, but there may be the odd occasion that I want to print these out. They're big files - 4752px * 3168px - I want to make them smaller anyway - am I likely to see a loss in quality if I reduce them to say 3008 x 2005 and change the resolution to 300dpi?

 

[Grendel]

your 4752x3168 72ppi images will be 167.64cm x 111.76cm at 72 dpi. Therefore, if printed at 300ppi you would get a print size of 40.23cm x 26.82cm

So if you reduced them to 3008x2005 at 300ppi, you would get a print size of 25.47cm x 16.98cm

Hope that helps

 

[JustinParker]

Here's a convertor so you can work out what size and resolution gets you what although its in old school inches rather than metric.

 

[johnnyguitar]

I know that scaling up from 72dpi to 300dpi can lead to a poor quality print. If I make the image smaller, will scaling up still affect the quality of the print?

 

[JustinParker]

If you scale dpi up and dont change print size then your relying on photoshop to interpret extra pixels. If as in your case you are just resizing through changing the dpi and allowing the print size to be auto scaled to the new smaller image size 15.8"x10.5" your not losing any image data. When you then reduce the image size further to your target image size you then rely on photoshop determining what pixels to keep and which to discard however at 300dpi you should be unable to notice any difference in quality.

How are you viewing the original image on your desktop at the moment? I'm guessing its auto resizing on screen anyway so you can see the full image.

 

[cannockwolf]

dont forget to sharpen again once you have resized

 

[Chaz Photos]

I know that scaling up from 72dpi to 300dpi can lead to a poor quality print. If I make the image smaller, will scaling up still affect the quality of the print?

You image have NO dpi set all you have is the number of pixels DPI or PPI only comes into play when you output a image.
Take the number of pixels and divide it by what ever dpi you want to get a size OR reverse this sum to pixels dived by size to see what dpi you will get.