Use the full 1600×1200 source and choose 16:9. Keeping the full width requires height 1600×9÷16=900. The crop removes 300 vertical pixels, so a centered frame removes 150 from the top and 150 from the bottom.
The exact rectangle is 0,150,1600,900
Read X=0, Y=150, width=1600 and height=900. PNG export creates exactly 1600×900 pixels. Choosing JPEG or WebP keeps those dimensions but changes the encoding and usually the exact byte count.
16:9 is a shape, not a platform guarantee
A site may later scale, recompress or overlay the image. Check its current pixel minimums and safe areas separately. CropFrame deliberately does not claim that one 16:9 file is automatically valid for every banner, video or social destination.
Keep the crop in its proper scope
CropFrame creates a new Canvas-decoded image and does not preserve metadata, provenance, measurements or evidentiary fidelity. Use it for ordinary digital publishing and design. Do not use it to prepare identity, medical, legal, inspection, emergency, navigation or other safety-critical imagery, and independently verify every important result.