- Open The original photo into Photoshop [1261px X 1546px]
- From Tools Select Crop Tool (c)
- From the Crop Tools Properties bar Set the Width 800px And Height 600px or other custom value you want
- Drag into image the area you want to Crop with fixed size 800x600px
- Press Enter and Crop
- And here the new size of image.
- Save the document with new filename
