Can we see the image, please?
Community MX Partner -
Adobe Community Expert
Author - Lynda.com
Author: Peachpit Press
1 person found this helpful
Images are not in inches. Images are in pixels. The dpi only matters when you print, as that will determine the scale for printing. The data is determined by the pixel dimensions and color information. Your image is 750x1050 pixels.
Increase the canvas size so you have room to work.
Draw a white rectangle 1.5 times the size as your image.
You'll need to rotate the white rectangle so that the edge lines up with the diagonal of your image.
Er...this is trigonometry. The tangent is the "opposite" over the "adjacent" (sides, that is). Taking the arctangent of (1050/750), we get 54.46 degrees. Depending on which way you want to slice your image, rotate the rectangle by that or by 90-54.46=35.54.
Move the white rectangle to cover the half of the image you want to keep.
Select the white rectangle and the image. Use Modify > Mask > Group as Mask.
Select the masked, triangular object, copy and paste it. Take the copy and flip it both horizontally and vertically.
Awesome math and nice precision in this technique! Nice work!