save option in pi12

[su1300]

I want some advice to save a picture in pi12. Suppose I want to resize my digi. camara's pic. for lab print in 4/6(jpeg). in adobe photoshop... I open the image( obviously this image is very large in size as I took it in my camera with best reso. & pixel)..... duplicate the layer...... do the necessary photo currections...... crop it in the size of 4/6 and save it in jpeg. This way I get my 4/6 print in 300 dpi resolution which is required in lab. But how I do this in PI..... as I can manage all things accept 300 dpi file. how I create i file of 300 dpi (if possible in one click). Also what will be save settings when I save it.One thing more, how I edit my picture, remain intact my original.

what is your opinion about save picture quality between photoshop 7 and PI12?

[Xyzzy2]

In PI11 you set resolution with Adjust>Resolution option.

If you want to edit picture retaining original, well, make a copy of the file and work on copy...