Can I change resolution of a photo without losing any quality, for Retina ready photos?

Question

Hi there
I would like to prepare some photos for Retina display screens (not for printing) and was told that in order to do this, I need to increase the resolution of my images from 72dpi to 240dpi.
Many of my original photos are 3000 x 1875 pixel size at 72dpi resolution. What I wanted to know is that if I uncheck 'resample image' in the 'image size' dialogue box and increase the resolution from 72dpi to 240dpi, will my image suddenly be Retina ready without ANY loss of quality?
I find it hard to get my head around the fact that you can simply raise the resolution of an image in this way with no adverse affect to the quality.
If anyone can help me with this, I would be very appreciative.

Answer 1

eadenha11 wrote:
One last question to clarify if I may: On a website where I have small fixed photos of 568 x 376px, what image size should I be uploading at to make this size of photo 'retina ready'?
I had previously mentioned above (with a link to support) that images for retina should be doubled in size. With your required pixel dimensions of 568x376, ideally you should be making them 1136x752. In HTML, your image code would look something like this:
<img src="img_1136x752.jpg" width="568" height="376" />
If you wanted it to be fluid, you could then overwrite that in the stylesheet by adding something like:
img.fluid {
     max-width:568px;
     max-height:376px;
     width:100%;
     height:auto;
<img src="img_1136x752.jpg" width="568" height="376" class="fluid" />