Banding issue in local tone map

[cinclus]

Hi,

Having just upgraded to PSP X4 SP1 (14.1.0.5), I spent some time yesterday exploring the tonemap layer feature on a few landscape images. The images were in different formats, like TIF, pspimage and jpeg. Some were in color, other in b&w. A couple of the images were high-quality scans, the others were from digital cameras (Nikon D200 and D700).

Not wanting to overdo it, I applied the tonemaps moderately. In addition, I used a few other layers like HSL, curves etc., all of them used in very moderate levels (e.g., slight desaturation and very modest S-curves). The results were very much to my satisfaction. Looking at them in large format on my monitor, I began thinking of using a few of these, and similar, images for an upcoming exhibition.

Then, I noticed the banding. I became aware of it when I reduced the displayed size of the images. I tried image after image, and found some banding of all of them. Having become aware of it I was also able to spot it on pictures in larger formats.

The banding is rather vague but becomes more evident when the image is reduced in display size, or when an image on the wall is viewed from across the room. It follows the form of the image, presenting itself as a vaguely darker, rather broad band about halfway between the image borders and the image center, in the same aspect ratio as the image itself. I am not sure what constitutes the band but somehow, at least a certain amount of pixels appear to have darkened, following a certain mathematical pattern, forming a somewhat darker rectangle within the image rectangle.

By disabling the other layers I found that the tonemap layer was responsible for the banding. Exaggerating the tonemap, exaggerating the image contrast and/or sharpening the image will make the banding more prominent for illustration purposes.

I would like to work more with the tonemap feature but need to know if there is a way around this problem, or if it will will be addressed in SP2.

Would Corel please look into the issue?

[teknisyan]

Hello cinclus,

Not sure if other members will be able to provide a workaround but I have already reported your issue and rest assured that our engineers will look into your concern.

[Simone Corel UK]

Hi cinclus

I'm going to send you a private e-mail. I need a sample file with before/after. It' always difficult to reproduce thing like that.

Simone

[cinclus]

Thank you for your replies, Abiel & Simone. I have e-mailed the files you requested, Simone.