Masters and Metals

Tony · Post by **Tony** » Fri Oct 21, 2011 7:34 am

In my DCG journeys I've taken holograms of coins. Since they are generally bright there is not a need for an H1 to H2. But I wonder.....

If I weren't lazy.... if I took a shot at a coin and made a DCG master then shoot an H2 would the metal "color" be reproduced?

Hey by the way where in the heck is Dinesh??? I miss my early morning read with coffee, may have to switch to tea

Martin · Post by **Martin** » Fri Oct 21, 2011 7:50 am

Tony wrote:In my DCG journeys I've taken holograms of coins. Since they are generally bright there is not a need for an H1 to H2. But I wonder..... If I weren't lazy.... if I took a shot at a coin and made a DCG master then shoot an H2 would the metal "color" be reproduced?

In my opinion this is mainly a bandwidth issue - "metal color" meaning broadband. So if you had the same DCG layers processed as usual, yes, you'd get the same metal color effect.

Dinesh · Post by **Dinesh** » Thu Oct 27, 2011 2:17 pm

Tony wrote: may have to switch to tea

Gawd forbid! But, if you do have to switch to tea, make sure it's a good British tea and make sure you have jam with it!

Anyway, in answer to your question,

Tony wrote: if I took a shot at a coin and made a DCG master then shoot an H2 would the metal "color" be reproduced?

It depends on the bandwidth, the central frequency and, more important, the variation of the sheen across the surface. A metallic object is a specular reflector, that is, it reflects almost like a mirror. In this situation, there's a desaturtion of colour roughly in the middle of the object - the sheen - which makes the centre glare. For objects like coins, this is what you have to reproduce because this is what is characteristic of a metallic coin. To do this, you have to illuminate the original object in such a way that there is more reflected from the centre -ish of the coin at the plate, but not too much more. Too much light off the centre will just overexpose the centre and you get a hazy grey-black colour; too little light (in other words, if the illumination is too uniform across the coin) and you lose that sheen/glare effect. Just the right amount of increased light and you'll saturate the dcg and create more broadband in the centre of the coin than the edges. The point here is that you need to vary the bandwidth across the coin, so that the centre is desaturated

There is one other effect. Silver halide is a narrow band material. Therefore, when you make the H1, you'll simply see a brighter centre. The broadband variation that happens with dcg won't happen with silver. You have to judge just how much brighter the centre of the coin is in silver and relate that to how much of a broadband effect you'll get in a softer, more wideband medium like dcg.

It can be done. Take a look at the bottom of this page ( http://www.3d-expressions.com/gifts/ ) scroll down to the bottom and the right hand image is coins from silver H1 to dcg H2. I overdid the brightening of the coin centre so I got a few greenies, but this was done about 6 years ago.

Kiffdino · Post by **Kiffdino** » Fri Oct 28, 2011 5:09 am

superb gallery Dinesh, you should post that link in the gallery section

Tony · Post by **Tony** » Fri Oct 28, 2011 9:33 am

Ahhh that was a good cup of coffee

Good to have you back Dinesh!!

Dinesh wrote:The point here is that you need to vary the bandwidth across the coin, so that the centre is desaturated

I wonder if you push it further if you can get broadband white? Just a thought

Dinesh · Post by **Dinesh** » Fri Oct 28, 2011 11:08 am

Kiffdino wrote:superb gallery Dinesh, you should post that link in the gallery section

Thanks! Ok, I'll post that on the gallery section.

Dinesh · Post by **Dinesh** » Fri Oct 28, 2011 11:10 am

Tony wrote:I wonder if you push it further if you can get broadband white? Just a thought

Certainly! In fact this is Augie Muth's signature work. He does all his dcg's in white.

Johnfp · Post by **Johnfp** » Tue Nov 01, 2011 6:07 pm

Dinesh, sorry, but I have to disagree on one point. Augie surely does not do ALL his DCG holograms in white.

He has mstered whites and pastels. A lot of his fine works are layered pastels. I love them more then the whites. I think the gift of mastering whites can really add to the pastels.

Dinesh · Post by **Dinesh** » Fri Nov 04, 2011 11:54 am

Johnfp wrote:Dinesh, sorry, but I have to disagree on one point. Augie surely does not do ALL his DCG holograms in white.

He has mstered whites and pastels. A lot of his fine works are layered pastels. I love them more then the whites. I think the gift of mastering whites can really add to the pastels.

John, you're right. He doesn't do ALL his dcg's in white. He showed a set of koi fish at SPIE a few years back that were orange. But he is known for that pearly white he achieves. As a matter of fact I asked him once how he achieved it. He said that he has a set algorithm which, if followed, gives him his white sometimes. He then rejects those that aren't white.

Johnfp · Post by **Johnfp** » Fri Nov 04, 2011 2:31 pm

I will have to say more then once I have seen a natural color come out of DCG. Especially metals. Silver coins look silver, gold coins look gold, copper looks copper. Something very interesting there that to me does not follow the rules.