The Photos app in Windows 10 will automatically enhance the quality of your photographs. It will straighten, crop, brighten, adjust contrast and change other qualities of the image to make it look good.

But if you wish, you can easily disable this auto-enhancing feature.

To do this, open the Photos app, click on its Settings. Under Viewing and editing, you have to disable Automatically enhance your photos feature, by moving the slider to the Off position.