And what exactly? The DPI of a document does not change when you resize its pixel dimensions. Conversely, changing the DPI must not affect the overall pixel count. Either way, it's absolutely not clear what you are asking and you need to explain better.
By using interpolation to change the number of pixel in the new re-sized image. Note I wrote new Image when you resample an image not a single pixel from the original image remains intact all the pixels in the new image have been generated via software you loose some image quality.
In Photoshop CS4 when I resize it retains the same dpi along with the new size.
In Photoshop CC when i go to resize - specifically when I go from 48" x 32.843 " @ 300dpi to 48 x 32'" it changes the size to 46.767 x 32" and retains the 300dpi. I want it to resize at 48 x 32" at 300dpi. What am I doing wrong?
Are you checking resample in the image size dialog? Also undo constrain. Changing the Aspect Ratio is asking for distortion. Your not doing anything wrong. By default constrain is active the width and height are linked If you change one Photoshop will change the other. If you want exactly 48x32 you need to crop off some pixels.
Its simple math your image is 48"x32.843" 300DPI so its 14400px by 9852.9px
you want an image that is exactly 48"x32" 300DPI so its 14400px by 9600Px you have an extra 252.9 pixels in height.
Now 48" x 32" is a 3:2 aspect ratio most DSLR capture 3:2 images How many pixels did you start with? You now have around 142MP. Also a 4' wide picture does not need to be 300DPI...
In Image -->Image Size make sure Resample Image is checked. Additionally, if you want to keep the same proportions make sure Constrain Proportions is checked.
He is trying to change Proportions but should use crop not image size