I'm so confused! I'm sure I'm missing something very simple. But when I create a new file in Photoshop that 320x240px at 300ppi then save that out as a JPEG and try to place onto an Illustrator artboard that is also set up at 320x240px at 300ppi the image I'm placing is half the size. Aren't they supposed to be the same size? What am I missing?
You have to take into account two things:
- Illustrator was originally built for print, not screen design.
- Illustrator canvas is shown and measured at 72dpi.
What does this mean? It means that:
- If this is for print (I guess, hence the 300dpi) you should create your Illustrator document in a physical size: mm, cm, in.
- If this is for screen, do create your illustrator document in pixels BUT prepare your image assets in photoshop at 72dpi.
320x240px @ 300dpi equal roughly 27x20mm. Try creating an illustrator doc with those physical dimensions and try placing your image again, see what happens.
Illustrator is a vector based software built for print but as time moved forward, it began to support other profiles like Web, Video and Film and even Devices.
The key is to make sure you're choosing the right kind of document when creating one. Take a look at the image below to see how the settings change depending on the profile you choose.
Answering to your question, if you chose the Web profile and place the image you created on Photoshop, it should keep the same size. As MrMerrick mentioned, it's important you use the same measuring units in both softwares.