Every so often I have an image that requires a perspective adjustment as well as a rotational adjustment (often from when I have taken ‘walking’ shots of staff moving along a corridor - I often shoot at between 35-50mm and walk backwards as they move forwards).
I typically adjust the perspective first (using the 8 point tool) and this often makes the rotation acceptable, but there are times it still needs adjustment. Sometimes though the rotation when applied after the perspective shift looks weird (it can look as if the image has rolling shutter). In this instance I undo both changes and then apply the rotation first and then the perspective shift.
So, my question:
Is there an empirically correct order to which these two adjustments should be applied or is it a matter of a bit of trial and error to see which order works best for any particular image?
I’ve decided that I’m going to continue with my current workflow (which just happens to be the one that aligns with the Co-Pilot result) as it does seem to result in the best outcome for the vast majority of images. I’ll only then deviate if I feel artistically the result isn’t to my liking.
I’ve been running into the poorly levelled perspective correction issue lately, as I’ve been using perspective more. You’re right: PhotoLab should probably put in a level rotation with its automated perspective correction. Afterwards one could choose to make the image unlevel again.
For manual corrections, the auto-rotate could be skipped.
By rotation, do we mean Horizon adjustment/leveling?
I find that when I apply automated perspective adjustment (which is default, using the “magic wand” icon), Horizon also gets adjusted automatically. These can then be turned off or adjusted to taste. But for challenging scenes I might find it best to start from scratch with adjustments neutral, then decide from the image which changes to make first. If central verticals are crooked or if all horizontals are crooked, I adjust Horizon first. Then Up/Down gets adjusted until the verticals nearest the edges of the frame are truly vertical. If they’re uneven, I revisit the Horizon setting and continue tweaking. Any further horizontal line correction might need Left/Right adjustment, which tends to leave vertical objects properly vertical.
There are times when this process is quite difficult to get right. I might have to reverse the order and start with Left/Right adjustments. Occasionally, I will decide that not everything needs to be lined up perfectly - it might be better to leave perspective adjustments incomplete or even reduce distortion correction or make a diagonal Volume Deformation adjustment.
When I use the Volume Deformation adjustment, I try to do that before any Perspective adjustments or cropping, since adding it in later can mess up those settings. But this isn’t always necessary.
I find that using lines tools does not always correct both rotational and perspective issues. In such cases, I first correct the rotation and then use the sliders to correct perspective distortions. This can take a few iterations but it gets me the accuracy I want.
For me, the merits of the picture determine the order. I very often have a tilt of about 1 degree in my horizons (I think my right shoulder is a fraction lower than my left). If there’s significant keystoning in the image I usually correct any tilt first, so that the perspective correction doesn’t add distortion. But if there’s relatively minor keystoning then simply letting the perspective correction magic wand do its thing is often sufficient.
My work doesn’t require the absolute precision of, for example, architectural photography - it mostly involves people in their environment. Only occasionally, I find a perspective adjustment can distort the look of a person in a way that just quite ‘look right’. I then experiment with the image to get to a point that is ‘mostly correct’ in terms of parallel lines and horizon. Hope that makes sense?
