I'm currently using:
OS X EL CAPITAN
iMac (Retina 5K, 27-inch, Late 2015)
Photoshop CC 2018 - 19.0 Release
The issue I'm having is that whenever I try to open a new document for web, the dimensions I use appear to be smaller than they should be.
Eg. 1000x1000px square looks like a 300x300px square.
When I export the image to jpg or png. it saves at the right dimension size but all of the content is pixelated and I've never encountered this before in the past.
If I try to save it as a PDF, the file becomes corrupt, but this problem doesn't happen when I work with print.
Hopefully I've explained this clearly enough!
This is a jpeg at 100% quality!
The pixelation isn't obvious because the screenshot has been scaled down but trust me, it's happening!
If anyone can help me, that'd be amazing because I feel like I've taken crazy pills!
[Here is the list of all Adobe forums... https://forums.adobe.com/welcome]
[Moved from non-Cloud forum to Program forum... Mod]
It's because you're running a Retina display.
You can double check the resolution of your images by choosing Image menu > Image Size.
Check out file formats here: File formats in Adobe Photoshop
Jpg is good for contone images like photographs (no transparency)
Gif is good for solid color and animations (transparency)
PNG has an 8 bit option for solid flat colors like your example or photos with transparency (24 bit)
And don't forget the native PSD format - excellent for placing images in InDesign.