Vignette Inverse or Radial Gradient - Adjusting exposure for darkened corners

[adamvanspronsen]

Hi there,
Anyone know how to adjust images that have darkened corners? I would like to autotone many images that have some lens shading in the corners. In Adobe Lightroom, I can apply a radial gradient for exposure to adjust this - but I need a script to run on a computer that will not have Lightroom and was hoping something like ImageMagick could work.
Any ideas or solutions for this?
Thanks.

[fmw42]

Imagemagick can create and apply radial gradients. Please post an example image.

[adamvanspronsen]

Here is an example Image. As you can see the corners are quite dark. I would like to auto-tone the images and adjust this dark corners from lens shading.

Any help you can provide would be greatly appreciated.

[fmw42]

How would you do that in Photoshop? I don't know of any anti-vignette tool? In Imagemagick you would need to create an appropriate radial gradient and then use that to apply some process to the image. I do not know how to figure out what radial gradient is needed automatically.

[fmw42]

You could also create your radial gradient using either: -vignette or radial-gradient: with an appropriate define. See https://imagemagick.org/Usage/canvas/#radial-gradient and PSEUDO-IMAGE FORMATS section at https://imagemagick.org/script/defines.php and https://imagemagick.org/script/command-line-options.php#vignette and https://imagemagick.org/Usage/transform/#vignette

[adamvanspronsen]

Thanks for this information, I will try this out today.

[snibgo]

If you don't know the vignetting applicable to your lens, the easiest way is to photograph a plain white card. Then divide any photograph taken with that lens by the image of the white card.

[fmw42]

See https://imagemagick.org/Usage/photos/#vignettation for that process

[adamvanspronsen]

Thanks for this information, I will try this out today.

[adamvanspronsen]

> How would you do that in Photoshop? I don't know of any anti-vignette tool? In Imagemagick you would need to create an appropriate radial gradient and then use that to apply some process to the image. I do not know how to figure out what radial gradient is needed automatically.

In Adobe Lightroom, there is a radial gradient option, then adjust exposure for that gradient.

[fmw42]

But you still need to know the correct radial gradient for the image vignette.