Issue with resizing images

[Madeline237078500hy7]

Hello, I have been having an issue with resizing images. As an example, if I reduce the width of a much larger image to 500px, it will show up in photoshop at 250px (I've measured the pixels with the screen grab tool/command+shift+4) and when I save the image and upload/open it elsewhere, it will actually be 500px but it will look like the image was enlarged from a smaller one, it'll have no sharpness. Are my settings completely wrong for what I'm trying to do? Thanks for any help in advance.

[davescm]

It sounds like you are using a screengrab tool with a high resolution retina screen and it is counting the effective pixels as displayed by browsers etc which double up the image size on retina screens and each effective pixel uses 4 real screen pixels.

Photoshop's 100% display does none of that (in fact it must not or we could not judge critical sharpness as all scaling introduces artifacts). Photoshop therefore  uses exactly 1 screen pixel to display 1 image pixel. This can make the image look physically smaller compared to browsers or viewers that double the image size on screen. If you want to simulate that doubling in Photoshop then use 200% zoom.

Dave

[NB, colourmanagement]

Dave is right about "measuring" an image using a screenshot. 

You wrote "I reduce the width of a much larger image to 500px, it will show up in photoshop at 250px",

but, your third screenshot seems to show it is correct at 500 px wide.

How are you detecting a 250px wide image in Photoshop?

neil barstow, colourmanagement net :: adobe forum volunteer:: co-author: 'getting colour right'
google me "neil barstow colourmanagement" for lots of free articles on colour management