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UltravioletPhotography

First attempt at IRG


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Today I tried to "shoot" (more to "generate") an IRG image. I took the visible light image with a piece of chinese BG39 (2 mm) on the lens, the IR image with a Hoya R72, processed the visible image to have the original green channel on the blue channel and the original red channel on the green channel (getting rid of the original blue channel), converted the IR image to B&W and then to red, and stacked the two images. The result is OK color-wise, but the images are clearly not aligned, and it's not that great in general. As a concept, I like it.

 

post-284-0-24405300-1605733748.jpg

 

Tell me if this is the right section for this kind of work (maybe the ultraviolet and multispectral was better) and also if I need to write the settings of the original images.

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I think I've been putting them in this section also? We tend to regard a lot of the infrared/visible mix photos as "infrared" and this is also true more generally online I've seen.

 

Photoshop improved the alignment a lot at the expense of losing some edges. I think you could do the same in Hugin also.

post-94-0-70480600-1605745884.jpg

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Naw, you don't need Hugin for this, not if you have Photoshop, it has an alignment feature.

Two photos, visual and IR. Stack them, then use Photoshop Edit, Auto-Align Layers.

Visual photo: move green channel to blue, move red channel to green, desaturate IR shot, move to red channel of visual shot. Auto balance.

Nice job, Andy.

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Naw, you don't need Hugin for this, not if you have Photoshop, it has an alignment feature.

Two photos, visual and IR. Stack them, then use Photoshop Edit, Auto-Align Layers.

Visual photo: move green channel to blue, move red channel to green, desaturate IR shot, move to red channel of visual shot. Auto balance.

Nice job, Andy.

Thanks -- I suggested Hugin because it's free, and I don't think Stefano has access to Photoshop. (I used Photoshop when I did it.)

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Currently, I don't have either programs. Reading what Bernard wrote about his processing technique (linked by David), you also have the issue of different magnifications, since the focal length of the lens is not constant for all wavelengths. It doesn't seem to be a big issue for me, but maybe I will need to solve it too.
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I have never had significant trouble with magnifications. The alignment algorithm (in any software) will handle small differences for you.
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I tried again. My camera has trouble focusing in visible light, apparently. This time I used a tripod.

 

Visible:

post-284-0-35934200-1605776405.jpg

 

IR:

post-284-0-50617600-1605776417.jpg

 

IRG:

post-284-0-24917800-1605776319.jpg

 

To convert the visible light image to R->G and G->B I use IrfanView, I do a channel swap (RGB->GBR, the last option) and then remove the red channel. Is this correct?

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What do you mean with "de-veiling"? I too noticed the IR frame appears "bubbly", maybe I need to shoot it changing the strong white balance I use to take the visible image. Is that the issue?
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Your last IRG looks like an old 1970's film shot.

Your IR doesn't look blown. You could just open it in your favorite editor and drop the EV by -1 or -2. RawTherapee might work for that as a free option.

 

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It didn't look overexposed when converted to B&W, but the channels suffered a bit due to the strong blue color of my chinese BG39, which makes IR appear very red. It actually looks almost normal in B&W.
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Ok, I'm back. This time I reduced the exposure of the infrared image, and did a quick in-camera white balance in order to avoid blowing the channels. I also put a paper tissue to white balance the resulting image.

 

Visible:

post-284-0-37989700-1605879628.jpg

 

Infrared:

post-284-0-17356100-1605879647.jpg

 

IRG stack:

post-284-0-43171300-1605879694.jpg

 

White balance on the paper tissue in IrfanView:

post-284-0-69403100-1605879729.jpg

 

White balance on the concrete in Irfanview:

post-284-0-29933200-1605879808.jpg

 

...it didn't work as I expected. Too much red when white balanced on the paper.

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White balance on the paper did work in PhotoNinja for me. Very similar to your concrete results:

post-94-0-47139300-1605913848.jpg

 

I think this may mean that you need to do a white balance on a region (average white balance) which you can do in PN by dragging around on the neutral object.

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Thanks Andy. It seems IrfanView struggles a bit at white balancing, it may not be the best software to do it. The image you obtained looks so natural and balanced (no pun intended), the colors are very nice.
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