Photometric web .ies lights making Photoshop render elements composition impossible.

[JeremyRamsay]

Hi, for an interior evening scene I would normally use Standard lights and render out the relevant Render Elements to take into Photoshop for compositing. But for this last scene I have used Photometric lights with an .ies file to control the light spread. Here lies my problem. Once I load the Render elements into PS in the usual manner the blending mode for most of these elements is 'Screen'. Screen has the effect of disregarding anything black in the image. But with these new Photometric .ies light Render Elements, the usual 'Screen' mode blending doesn't now seen to disregard the black entirely, rather leaves the blended image only slightly opaque or as if there is a mist over the image and not at all how it was when I was using standard lights. I've checked my setup and there's nothing I'm doing differently. I understand that even trying to explain this is tricky but if anyone in the know can help I'd appreciate it. Is there a click or a trick I'm missing for this, thank you.

[Chris MacDonald]

Could you perhaps post a screenshot or something?

[JeremyRamsay]

Hi, not sure if the upload is working.

[Nicolai Bongard]

While you are in photoshop, can you not just adjust the levels of the render element so that the blacks are completely black? That should remove the haze/mist effect.

[JeremyRamsay]

I could but that level adjusting would also affect the individual render element, meaning if I was on the Reflection pass and I corrected the black, then the Reflection itself would be altered. I was hoping there was a simple correct I wasn't aware of. Just as a test I've very quickly set up a scene with Standard lights and set up render elements. Brought them into PS and it's all working fine so this issue definitely seems to be connected with Photometric .ies lights.

I hope this makes sense as it's really tricky to even explain.

[Chris MacDonald]

Use a clipping mask so it only affects one layer?

[JeremyRamsay]

Yeah. the problem's not isolating the layer it's more about affecting only the black on that layer, I've attached the Reflection pass, once this is blended on the 'Screen' mode, the black would completely disappear and you'd just be left with the reflections that could be adjusted.

[Nicolai Bongard]

The closest thing i guess would be to open your reflection pass, press ctrl+alt+shift+e, then ctrl+shift+u to create a new layer copy that is black and white, then adjust levels so that only the really darkest parts are black and the rest is white, then invert it, thus creating a mask for the previously suggested levels adjustment so that it only operates on the darkest parts of the image, leaving the rest of your reflection pass unadjusted. Might have some weird results tho. You could also try selecting by color range on your reflection pass, to create a mask.

[Tommy L]

Im going to guess that you adjusted the contrast in the buffer. This may have brought your black level up above zero, hence cpontributing to the screen layer. You can either re-render and turn off the buffer adjustment or you can use a PS adjustment to bring the black back out of range.

[Chris MacDonald]

Yeah. the problem's not isolating the layer it's more about affecting only the black on that layer

 

Forgive me if I am missing something, but an adjustment layer (such as curves, or levels) would allow you to set your blacks to black? You can use the histogram to see where the black point is too.

[JeremyRamsay]

Nicolai – Thanks for such a detailed and thorough response, and not that I want to come down on your solutions but I’m using around 15 render passes for my post production, most on the Screen blending mode so I was hoping to get to the reason why this is happening, hopefully from the outset to avoid a lot of unnecessary post production.

Tom – I thought you had it there but going back into the file I can see I haven’t used any corrections in the buffer.

Chris – Yep, I can adjust the curves on the Reflection pass and that does help, but it also effects the reflections themselves. If I can’t get to the bottom of why is happening though, it’ll be the way to go. You’ve got me looking further into Photoshop than I’d been, thanks. It’s just a puzzler why this has to be done in the first place.

[Chris MacDonald]

Yeah, without seeing the vray settings, lighting, etc it's quite hard to diagnose the problem.

[Tommy L]

re-render a low res, see if your blacks are still grey. I bet you changed the buffer on the fly, if you did that whilst rendering on BB then it wont be retained in the file.

Seriously, there's no other explanation for it.

[JeremyRamsay]

Right, I'll merge everything in to new file that can't have any corrections, anywhere, and re-render, then proceed with the compositing, 2 versions, one with the .ies lights, and another with a quick spread of standard lights and see the results. I know it may sound like I should have done that to begin with but without the comments I've received, I was convinced it was an .ies problem so I couldn't have known. Thanks guys for your replies, once again evidence that cg illustrators are a canny bunch.