Image Filter for Exponential Exposure

[thomas]

Hi!

Just got Kray yesterday and I like it! Two things though:

1) Why do I sometimes get the 'This option only applies to FP images' when I want to adjust exposure in LW image viewer on the Kray render.
2) Is there a way to use the Kray Tone Blending plugin on a rendered HDR image? The preview looks great, but the saved out version seems to be the non-tonemapped HDR image. I know the setting I need (Exponential, 2.5, 1.2) but I don't have the time to re-render. I've tried an empty scene with the HDR image as a backdrop - through the compositing tab - and then rendering in Kray, but this only gives a black screen.

Any ideas?
Thanks!

Thomas, happy to join the fun.

[jure]

Hi!

Just got Kray yesterday and I like it! Two things though:

1) Why do I sometimes get the 'This option only applies to FP images' when I want to adjust exposure in LW image viewer on the Kray render.

Kray will output HDR image to LW image buffer when HDR image format is selected and limit DR is set to "dont limit DR".

2) Is there a way to use the Kray Tone Blending plugin on a rendered HDR image? The preview looks great, but the saved out version seems to be the non-tonemapped HDR image. I know the setting I need (Exponential, 2.5, 1.2) but I don't have the time to re-render. I've tried an empty scene with the HDR image as a backdrop - through the compositing tab - and then rendering in Kray, but this only gives a black screen.

Any ideas?
Thanks!

Thomas, happy to join the fun.

Well tonemapping the image actually goes against HDR image concept. When you render to HDR you wouldn't want to use any tonemapping, since you can use whatever tonemapping you like on HDR in post.
But you still can render to HDR with tonemapping on but you'll effectively loos all the HDR data and end up with regular 0-1 range image.

Why you are seing different image in HDR than in preview is probably because your image viewer didn't properly apply gamma correction to the image. Try changing gamma to 2.5 and you should get correct image.

[thomas]

Hi Jure,

Thanks for the reply.

Answer 1) Makes a lot of sense!

Answer 2) then:
I get what you are saying but I want to use the EXACT same exponential tonemapping that Kray has used - it's very beautiful, and Photoshop doesn't do the same exponential tonemapping. So I still have the question: is it possible to apply the Kray tonemapping to a HDR? As you do correctly imply, the output does not need to be HDR anymore. The thing is, I always save a HDR copy because it gives me the maximum flexibility. I would just love to test out different (blended and or exponential) tonemappings afterwards, and the Kray plugins seem perfectly suited for this, except there is no image filter plugin.

As an additional question: can I use a HDR image as a LW background, and have this show up in the Kray render? Right now all I see is black!

Thanks,
Thomas

[jure]

Hi Jure,

Thanks for the reply.

Answer 1) Makes a lot of sense!

Answer 2) then:
I get what you are saying but I want to use the EXACT same exponential tonemapping that Kray has used - it's very beautiful, and Photoshop doesn't do the same exponential tonemapping. So I still have the question: is it possible to apply the Kray tonemapping to a HDR? As you do correctly imply, the output does not need to be HDR anymore. The thing is, I always save a HDR copy because it gives me the maximum flexibility. I would just love to test out different (blended and or exponential) tonemappings afterwards, and the Kray plugins seem perfectly suited for this, except there is no image filter plugin.

As an additional question: can I use a HDR image as a LW background, and have this show up in the Kray render? Right now all I see is black!

Thanks,
Thomas

If you open your hdr in Photoshop or alike then it will apply gamma correction to your HDR render. All you need to do then is to take away this gamma by applying 0.45 gamm correction and your render should look like the one from Kray preview.