I'm bringing a png file into photoshop. I have to crop the photo to 600x900 to fit it in a space within optinmonster. When I select a 600x900 space the subject and product in the image will not fully fit into the 600x900. So I resized the image downward around 35%. So now when I go to select the 600x900 area, it is the same fit as before I down sized the image. I thought that because the image was smaller I would be able to select more of the image into a 600x900 area. I'm doing Image > Image Size , reducing the pixel width from 4000 to 1500, and leaving the resolution the same, and doing an automatic resample. Attached is a screen shot.
Anyone got any ideas about what I shoud do differently to get the result I want?
You are working on an image on a background layer. When you resize the image, it resizes the "canvas", and everything will go with it.
The VERY easiest way to avoid issues with this, is to create a new 600x900 document and then place your png into it. That will create a Smart Layer, which will retain as much detail as possible, as you resize THAT layer to fit your canvas.
When you resize using Image > Image Size you are resizing everything in the document. If you want to resize only one part so another part seems larger you must resize parts or layers independently using Free Transform or after using Image Size use Free Transform with Smart Object layer and enlarge it (only content on Smart Object layer).
If you do not have content on Smart Object layer be careful to not enlarge that content. It will work to shrink content once on that layer but multiple scaling will harm quality.