The size of the file which will load if selected will appear. 1024 by 1536 means 1024 lines by 1536 pixels or a 4.5 MB file. This is in order to get the best color balance. Click OK to load the image to the screen. Apply levels to boost the perceived contrast - to taste.
Levels Bring in the left and right arrows to where the histogram begins.
Be sure Preview box is clicked so that you can monitor the results as you do it.