Is there a camera effect that can change this true color?

I have a theoretical question and i am thinking about aluminum specifically, since it due to low emissivity and high reflectivity, should appear silvery-gray in daylight conditions. When the metal has a true silvery color at a certain temperature in air in daylight, and in the case of aluminium has a very rapid cooling effect and often is many hundreds of celsius cooler immediately when poured in air compared with iron that always will keep a high temperature, then there should not be any camera effects that on video could turn this what for the human eye is a true silvery color, into a strong orange color?.

So i am not only talking about a natural phenomenon, that has to do with temperature and how a molten material looks when molten for the human eye. I am talking about a camera effect, if there exist a camera effect in CMOS camera sensors or with any other cameras, that can change the true color of a molten metal in daylight, the color that is true for the human eye, in this case a silvery color, into a true orange color. My guess would be that it would be impossible for a camera in daylight to change the true color of a molten silvery metal into a true orange color, and that you can find many videos with simple cameras where everything looks true to life.

I am told that "It cannot be done without post-processing.The main issue is that the camera must operate on the light received from the scene. In 3d graphics terms, this is diffuse light. It has shadows and is affected by the angle between the surface and the light. The glowing effect of molten metal is unaffected in this way. It glows equally in all directions, regardless of lighting, and has no shadows (in 3d graphics terms, it's more like an ambient light).

There is no way to distinguish between a shadow which hides part of the metal from the light and a piece of dark paper. Thus there is no way to make that shadowed region glow without also making a piece of dark paper glow the same.

Also, the heat patterns are complicated. When I was casting aluminum ingots for fun, the edges and corners cooled first. This caused the center of the ingot to glow brighter than the edges. In some lightings, the shadowless omnidirectional light of the glowing center made it look like I was seeing through the metal into the core of the ingot. I was not, of course, but they eye has to do really strange things to make sense of glowing objects, and mine decided it looked like a glow from the core.
Best bet: film the molten aluminum in a very dark environment. That will make the glowing effect more pronounced when compared to the diffuse lighting because you'll have a lower shutter speed or lower f-stop to capture the low-light scene. I created some interesting photos that way with a flash and then a long exposure while moving the camera. The flash captured the metalic grey, and then the movement created a glowing ghost that followed.

The cameras will capture the light that is present. If the light isn't present, they wont capture it. They might saturate, but that saturation will rarely result in the correct orange glow associated with high temperature metals. What you capture on your camera and then edit for say DVD should not end up changing unless you change it specifically in the edit."

Does this mean that you haft to specifically add the orange color intentially after it has been filmed in a studio with software if you for some reason want to manipulate the colors in the video?. Something that would be televised as a regular documentary or something like this would never have its video manipulated into changed colors like this, it would only be for the film/entertainment industry maybe?.

So i am asking if it is right that the only possible way to change the true silvery color of the molten metal in daylight with post-processing (that he is talking about) is when you intentionally add a new color with video tools and software, it will not happen by itself in some standard video process while you prepare the video for a DVD-release right?. I am both thinking about old cameras with CMOS camera sensors and new cameras. I dont see how it would be possible for the true colors to change like that by some standard process without any manipulation with software.

I know that there are some colours/saturation values that will not be recorded by the camera - depending on the cameras dynamic range it will become white at a certain level and so depending on the cameras capability you will get a certain range of values up to where the camera sees the colour as too hot and gives a white value only. But i think for most cameras, even older CMOS camera sensors, you would need a temperature maybe above 2000 C and something like burning magnesium for a constant strong white color. If you had some pure aluminium metal powder and iron oxide metal powder reacting and producing molten iron at 1500 C and above this temp, you should have no problem seeing the orange molten iron if it was falling in the air, and if there was bright white big round ball shaped flashes in the air from the powders, the white flash would be able to block the orange molten material in the air so that you at this moment only will see the bright white flash and no orange molten material, there is nothing making this impossible on a video recording, as we understand it.

Strictly speaking it’s not possible. The difficulty is compounded due to the lack of pigmentation of the metal. Adjusting any parameter that affects grey is going to be global.

Temperature is the only real tool at your disposal. The hot metal must be kicking out IR. If you could tune the frequency and density of filtration maybe you could “color” the metal enough that you could grab a piece of it with a LUT. The trick here is leveraging optical frequencies available to the camera yet invisible to humans. Aluminum in particular has a low emissivity coeficient so perhaps.......I’ m gonna stop there.

Good Luck

Strictly speaking it’s not possible. The difficulty is compounded due to the lack of pigmentation of the metal. Adjusting any parameter that affects grey is going to be global.

Temperature is the only real tool at your disposal. The hot metal must be kicking out IR. If you could tune the frequency and density of filtration maybe you could “color” the metal enough that you could grab a piece of it with a LUT. The trick here is leveraging optical frequencies available to the camera yet invisible to humans. Aluminum in particular has a low emissivity coeficient so perhaps.......I’ m gonna stop there.

Good Luck

When you say that adjusting any parameter that affects grey is going to be global, do you mean with this that all the colors in the video will be affected and noticeably different and not true to life?, or do you mean that a colour change will only affect the same colour in other parts of the image?.

I am doing a paper about metals where i will use alot of cameras to capture some effects of the metals and metal powders in experiments, i would like to explain this in the paper. If i send you some bucks for your time, would you be willing to take some time and explain with more details the problems with all this due to the lack of pigmentation of the metal and what all this means in a more scientific way?.

i guess by IR you mean infrared, but i dont know what you are getting at here, i dont have alot of knowledge about cameras i can tell you but i am learing.

A TV team making a documentary about nature and landscapes might want to make the color of the ocean or sky a bit more blue in in post-production, but when you have a TV-team that films something as simple as molten stuff/metals in a fire in daylight or if you film in a aluminium foundry, you would never in post-production as i understand it use any software to change a true silvery color of a metal into a strong orange color, while every other color in the video is true to life, the flames in the fire or the colors of the surrounding objects in that environment, no production team that was about to show something on TV or in a documentary from single camera shots of molten metal in a fire or in a foundry would change the true color of only a molten metal in a extremely pronounced way from true silver-grey to true orange, because it would make no logical sense for anyone to change a true color like that, this is not the same scenario as wanting to show stronger colors of the sky or the ocean, i think you would agree with this.

So what i am getting at is that the cameras will capture the light that is present. If the light isn't present, they wont capture it. A true silvery color, in this case a cooling molten aluminium falling in the air in daylight, with its low emissivity and high reflectivity, giving of a silvery-grey color, when captured on your camera and then edit for say DVD should not end up changing unless you change it specifically in the edit, which in this case would be totally illogical and would not happen.

In this video you can see molten aluminium that is pouring and burning flames next to it videoblocks.com/video/workers-in-a-foundry-pouring-liquid-aluminum-to-a-sand-cast-rfizxps0mjotxbs4b this is the type of thing that i mean, you would not change this into something else, neither the flames or the molten metal would be changed, just like it should not be changed in another environment outdoors in daylight.

I will send you a PM also with some contact information if you would be willing to help out with this part in my paper. I am a bit curious what kind of background and education you have with cameras if you don't mind sharing this.

Thanks for your input and help in advance. I really appreciate it.

My suggestion is based on the idea of using Infrared sensor contamination to pull a qualifier for a LUT.

A Look Up Table is a conversion matrix. You can use a LUT to isolate color channels and manipulate them in-camera in real time.

Black, grey, white (lift, gamma, gain) are tied to the primary RGB debayer of the sensor, any change that changes grey is going to change the overall white balance of the scene. A LUT targeting grey would be of little use here as all of your midtones would be selected.

IR contamination commonly manifests as a shade of red. If the metal could be heated to a certain degree it may emit enough IR to cause the grey to be interpreted as ruddy tone by the sensor the way black leggings would be. The resulting tone could be grabbed by a LUT with more precision than grey.

I have zero knowledge about the emissivity of metals save the black body radiator that is the metric for color temperature, which is incidentally the same as temperature.

Unless the end goal is actually to prove it's possible, I can't see how it would be worth the time or effort to try and do anything in-camera that could easily be a couple clicks in post.

Good Luck

P.S. Thank you IR leg guy for posting this, I am borrowing it for this discussion.

KmPu-WGdyUg.jpg.980e0be68c282ee08f983134f1fc9575.jpg (90.08 KiB) Viewed 607 times

My suggestion is based on the idea of using Infrared sensor contamination to pull a qualifier for a LUT.

A Look Up Table is a conversion matrix. You can use a LUT to isolate color channels and manipulate them in-camera in real time.

Black, grey, white (lift, gamma, gain) are tied to the primary RGB debayer of the sensor, any change that changes grey is going to change the overall white balance of the scene. A LUT targeting grey would be of little use here as all of your midtones would be selected.

IR contamination commonly manifests as a shade of red. If the metal could be heated to a certain degree it may emit enough IR to cause the grey to be interpreted as ruddy tone by the sensor the way black leggings would be. The resulting tone could be grabbed by a LUT with more precision than grey.

I have zero knowledge about the emissivity of metals save the black body radiator that is the metric for color temperature, which is incidentally the same as temperature.

Unless the end goal is actually to prove it's possible, I can't see how it would be worth the time or effort to try and do anything in-camera that could easily be a couple clicks in post.

Good Luck

P.S. Thank you IR leg guy for posting this, I am borrowing it for this discussion.

KmPu-WGdyUg.jpg.980e0be68c282ee08f983134f1fc9575.jpg

Thanks. Could you just explain a litte more what you mean by "The difficulty is compounded due to the lack of pigmentation of the metal." i am very curious of this.

Also, do you happen to have any suggestion for a expert or univeristy or someone that i could contact for more detailed and technical explanations of all this for my coming paper?.