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Problems with Darkroom 9.1 Core Green Screen 
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Post Problems with Darkroom 9.1 Core Green Screen
I recently carried out a thorough test of Darkroom's green screen functionality prior to doing my first 'live' job with it. I have to say that I was really surprised at the problems I encountered.

Attachment:
Source Image.jpeg

This is the original image. Not a good shot, just a test one.

Attachment:
ED Output.jpeg

This is the image straight out of Darkroom, using the default settings. Notice that the dress is now mottled and the girl's hair is matted. It is possible to improve things by tinkering around with the settings in Darkroom, but that takes time and slows the workflow down.

As an experiment, I took the same two images and combined them in Green Screen Wizard, again using the default settings. The results was fine. The trouble is that, whilst GSW does produce great results, I find the user interface is clunky. I hit upon the idea of using GSW in 'event' mode to automatically watch for incoming images, extract them from the background and then save them as transparent PNGs. The plan was then to use Darkroom to import the PNGs and combine them with the background and thus getting the best of both worlds.

Unfortunately, Darkroom was having none of it! Here's what happens when you open a transparent PNG in the photo workshop:
Attachment:
Transparent imported into Darkroom.jpeg


I spoke with Ian Griffiths at the Coventry meet last week and showed him the problem. He suggested that part of the issue was to do with the way I was lighting the subject and that it was perhaps a little over exposed.

I took onboard what he had to say and proceeded with Saturday's live green screen job. I took a great deal of care in ensuring that the lighting was better, but still had exactly the same 'mottling' problems.

By default, Darkroom seems to insist on using a "Hue" setting of 36. Dialling this down to 26 improved the image no end, as did tweaking the shadow settings. The first order of the night was for 14 copies of one print. The image was adjusted so that it looked right on-screen, then the job was sent to the printer. It was then that we discovered that print does not match the screen. To get an accurate print, we needed to dial the "Hue" down even further.

Following the chat with Ian last week, I sent a polite email to Brian at Darkroom explaining the problems I'd encountered. As yet, I've not even had an acknowledgement of the email.

Simon


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Wed Nov 02, 2011 10:03 am WWW
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Post Re: Problems with Darkroom 9.1 Core Green Screen
Awhile back ED rewrote the GS engine and because many felt the old one was better they introduced an option in set-up to either use the old or new ( in 8.9 ). If the option is still there in 9 have you tried the old engine ?

I know you are pretty clued up on ED so probably teaching granny to suck eggs but I presume with the png your not trying to use GS but just using standard borders ?

Whilst ED probably isn't the best GS tool! I've used it for some pretty bad situations and produced better results than your example so wouldn't think it's your image but Ian has far more experience with GS than me.

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Wed Nov 02, 2011 1:50 pm WWW
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Post Re: Problems with Darkroom 9.1 Core Green Screen
Simon,

I'm suprised Brian hasn't been back to you, might be worth resending in case it didn't get to him?

I just tried dropping a .png 'subject' image in to a GS border with no success, couldn't recreate what you got so I think it is as we discussed in Coventry, the software isn't able to accept a subject image with a clear .png background, it is looking for the green wavelength to drop out. See my samples below.

Half subject cut from greenscreen, saved as .png with clear background.

.png file added to known working GS border.

With my limited knowledge of how GS in Darkroom works I would assume that it just isn't designed to use .png's as subject images, perhaps as there appear to be different ways the .png process can interlace a clear background?

In your "Girl with a broken arm" photo how did you light the subject?


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Wed Nov 02, 2011 2:20 pm WWW
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Post Re: Problems with Darkroom 9.1 Core Green Screen
Thanks for the replies guys.

ian griffiths wrote:
With my limited knowledge of how GS in Darkroom works I would assume that it just isn't designed to use .png's as subject images, perhaps as there appear to be different ways the .png process can interlace a clear background?


When trying to import the transparent PNG file into Darkroom, I wasn't attempting to use the green screen function because I know that there isn't any chroma colour for it to work with. I simply created a border with a background graphic and then overlaid a smaller photograph on top into which I imported the PNG. I should point out that the PNG looks incorrect in Darkrooms viewer, so I am not surprised it gets it wrong when combined.
I should point out that in Windows explorer and photoshop, the transparent PNG gets rendered correctly.

Interestingly, if I add the PNG as a graphic, rather than a photo, it works perfectly. Of course, I can't then add a different picture without editing the border, so that's a non-starter.

Quote:
In your "Girl with a broken arm" photo how did you light the subject?

Single soft box at 45 degrees to the subject.

I can't quite get me head around why the 'blotchiness' appears on the dress. I've opened the image in photoshop and taken colour samples, and there's no green cast to it. Typically, the cream area is 208,192,167 and the black is 43,44,41. Her hair is 197,155,95.I f I sample the green background it is 79,130,55 - so there's a good separation between the colours.

If you look more closely at the dress, it appears that the artefacts are either triangular or diamond shaped, which is odd.

Duncan Harris wrote:
If the option is still there in 9 have you tried the old engine ?


Thanks Duncan, I will give it a go and see if it makes a difference.

Simon

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Wed Nov 02, 2011 4:34 pm WWW
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Post Re: Problems with Darkroom 9.1 Core Green Screen
I just had a reply from Brian at Darkroom and he suggested making sure that I selected 'green' rather than 'automatic' for the colour detection. Tried that, but it didn't make any difference.

I also tried as Duncan suggested, using the alternative method, and that did help make things a bit better.

Simon

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Wed Nov 02, 2011 6:55 pm WWW
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