I took a picture with a DSLR camera, but I noticed that there is a bit of perspective over the edges, as you can see in the example (especially in top right) enter image description here

My goal is to produce a texture, so it must be flat and equalized in the same way and in each point of the image. Is there a procedure to do that in Photoshop? Thanks.

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  • I can't really see any persepctive problems. If there are any, it's not noticeable. The only thing that looks like a potential problem to creating a seamless texture is the shadow along the bottom. – Billy Kerr Jul 22 '19 at 17:38
  • Just for curiosity I let GIMP create from your image a tileable piece of texture. It's in Filter > Map. GIMP took what it wanted and the result really was seamlessly tileable. Unfortunately the stoneless zone in the right top quarter is quite easy to notice repeating shape. A smaller piece without that dimple worked better. – user287001 Jul 22 '19 at 21:41
  • I guess it's because, comparing with top left corner, there're far less big stones, and small makes it look far. It's a texture, you can do anyting, clone, crop, fix distortion... – user2650501 Jul 22 '19 at 22:28

Correction so that it begins to seem to be photographed straight downwards - that does not exist except shooting a new photo. That's because nobody knows what's hidden behind the objects. If the pieces seem to be a little smaller on the top than in the bottom due the distance difference, that can be corrected by selecting all and applying Edit > Transform > Perspective. The amount of correction must be decided visually, there's no practical ways to calculate it without having some known pieces in the image or knowing the shooting angle, distance and the used lens. Here's one perspective adjustment:

enter image description here

As said, this is no fix, it compensates only some object size differences except the differences already were quite small, if we compare small particles. Actually my correction makes the image worse as a texture, because it exaggerates the fact that big stones are accumulated to the top half.

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  • Actually I took the pic straight downwards trying to facing the ground. I did it without a tripod and with the focal length set to 18. What if I use a good tripod and a bigger focal length? I have to change to completely avoid this and skip the edit in Photoshop? Thanks. – user840718 Jul 22 '19 at 15:55
  • You can compensate using a longer lens from further away - then the difference in distances will be minimised. A texture like this is unlikely to ever need to be perfectly perpendicular, so an approximation will probably work. I'd also look for an area slightly more homogeneous; that patch os small gravel will quickly be spotted in tiling. – Tetsujin Jul 22 '19 at 16:00

As already mentioned by user287001 The fix for existing shots is to attempt some guesswork with either Transform > Perspective, or Perspective Crop.

For this type of texture it's not vital to get the image exactly perpendicular to the ground, but when you come to doing more exacting surfaces, there are a couple of things you can try.

Bricks or paving slabs, of course can provide their own guide for you, but you could consider carrying something large-ish & square... a carpet tile, a tea-tray... you can drop on the ground & use as an estimate guide.

Alternatively if you use a longer lens from further away, you will naturally reduce the percentage distance change between near & far points.
Think of a simple close-up portrait, basically just face & neck.
Take a selfie with your phone & compare it to the same framing taken on a decent camera from 15 ft away with a longer lens.
Selfie... big nose, little ears. Long-shot... 'normal'

The issue with trying to do that whilst taking shots of the ground, of course, is how big a set of steps would you like to carry - which may take you right back to the carpet tile ;)

If you are too close to your subject though, even if it's one like your question with no really discernible scale, you will still find that identical objects near centre frame will look larger than ones towards the edges (unless you use a phone camera, in which case they will smear horribly at the edges instead ;)

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  • I'd like to understand if, at the same distance from the ground, a larger focal distance like 70mm could for sure flatten better, but doesn't add more noise than a 35mm? Maybe I'm wrong. – user840718 Jul 23 '19 at 0:22
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    Noise is not related to focal length, it is predominantly a side effect of light amplification at higher ISO values... which should never be an issue in daylight or with such a highly textured image. – Tetsujin Jul 23 '19 at 7:12

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