Today’s Question: When photographing a completed puzzle it is almost impossible to hold the iPhone [or any camera] parallel to the image. I remember that you have suggested perspective correction in Photoshop with Free Transform. Trouble is I can’t seem to get decent results. Perhaps I am doing something wrong. Any suggestions?
Tim’s Quick Answer: For this type of scenario I highly recommend using the Guided option for the Transform adjustment, which is available as part of the Camera Raw Filter in Photoshop, and in the Transform section of the Develop module in Lightroom Classic.
More Detail: It can indeed be very difficult to get the camera lens aligned perfectly orthogonal to the surface of a flat object you are photographing, such as a jigsaw puzzle or document. Fortunately, the Guided option for the Transform adjustment in Camera Raw or Lightroom provide an excellent solution.
In the context of Photoshop you can use the Camera Raw Filter. Start by selecting the image layer on the Layers panel (if you have added additional layers) and choosing Filter > Camera Raw Filter from the menu. Then click on the Transform button on the small toolbar across the top of the Camera Raw interface. The Transform button has an icon showing a box set at an angle.
On the right panel in the Camera Raw dialog, you’ll now see the Transform heading, with the Upright options directly below that heading. Click the button at the far right, with four overlapping lines, which represents the Guided option.
You can now drag and drop to draw lines that align with the edges that should be perfectly horizontal or perfectly vertical. You need to add at least two lines, and can add up to four. Typically, for example, you would draw two lines that correspond to lines within the image that should be perfectly horizontal (or vertical) such as the top and bottom edges of a puzzle or document.
In addition to the first two lines, you can add one or two more to further refine the result. In a situation such as the example of a puzzle, I would add four lines: one each for the top, bottom, left, and right edges of the puzzle.
Once you’ve finished drawing the lines for the Guided transformation, you can click the OK button to apply the change. At that point (or within the Camera Raw Filter) you’ll likely want to also crop the image, and possibly apply additional adjustments.