topic Re: Matching Paint RGB Values in Visualization

Matching Paint RGB Values

Anonymous — Thu, 11 May 2023 12:51:05 GMT

Dulux paints in Australia now give RGB values for all their colours. This is extremely useful to get the exact colour and see what it looks like on buildings.

Please go to http://www.dulux.com.au/html/specifier/colour_atlas.aspx select a colour and double click. It gives the RGB values as well as other technical information. I have tested in ArchiCAD and it gives the exact colour.

Now we just have to get the light right on the colours to get a clear impression.

Regards,

Re: Matching Paint RGB Values

Anonymous — Thu, 24 Jan 2008 08:39:10 GMT

Resene do as well:
www.resene.co.nz / www.resene.com.au

Re: Matching Paint RGB Values

Anonymous — Thu, 24 Jan 2008 22:06:49 GMT

Ha !
Well done... I asked Solver to supply RGB values, & they declined. Something about RGB not giving a true representation of the colour...? It's very good of them to do that, especially considering it makes it much easier for competitors to rip-off their colours ???

Re: Matching Paint RGB Values

Dwight — Fri, 25 Jan 2008 00:36:04 GMT

While it might be given merely as a lame excuse for not having the RGB values to hand, claiming RGB values to not be accurate color representation of a painted surface in a rendering has some validity.

I often encounter reluctance to share information, whether it is a developer unwilling to give a rendering of a building or a paint maker willing to do anything more than give a paint chip. Who needs the liability?

LightWorks users will know the frustration of seeing the fine Benjamin Moore paint line turned into fine LightWorks materials [color, sheen, roughness,etc, all included] and not be useable in Archicad because we can edit our materials. Some applications can lock material settings. We can't. Therefore Benjamin Moore and others feel that they are exposed to lawsuits when their materials are misrepresented.

The main reason paint manufacturers might not feel basic RGB values don't represent true paint color is that the user must still employ the color value in a material. In controlling the reflectivity of the material, color can be distorted. Pages 88+89 of my book discuss how to radically alter surface color using reflectance settings.

Re: Matching Paint RGB Values

Djordje — Sat, 26 Jan 2008 18:15:59 GMT

Don't forget the RAL colour AddOn.

Re: Matching Paint RGB Values

Anonymous — Sat, 26 Jan 2008 23:12:02 GMT

The benefit of the paint manufacturer supplying the colour RGB is the architect can show a very close image of the actual colour being proposed for the wall, surface, etc. I have just prepared a colour board for a building in Archicad, without little manufacturer colour chips, just from the RGB paint values. This was then simply be emailed to the client.

Generic colour systems do not reflect actual colours. I cant find the RAL Add On since ArchiCAD 9? The Goodies folder is no longer in the AC11 folder. Has it been placed elsewhere or is it a special Add On from elsewhere?

Re: Matching Paint RGB Values

Dwight — Sun, 27 Jan 2008 00:11:25 GMT

With all due respect, while the RGB value provided by the manufacturer is a good start and just fine for analytical views or a color board, sole reliance on the RGB values to establish color in a rendered material is poppycock.

Attached is a rendering of five objects with a uniform RGB value, each with different light reflection settings. Which one is accurate? Of course, i have exaggerated the problem with wacky settings, but get the point that even a few points of reflectivity inaccuracy will change the apparent RGB value.

This is just a caution to users that color is not that easy to replicate and that there's big trouble waiting.

Re: Matching Paint RGB Values

Anonymous — Sun, 27 Jan 2008 01:01:53 GMT

That is why I said in the first posting: "Now we just have to get the light right on the colours to get a clear impression. "

In terms of the 3D model the lighting is of incredible importance to get a true rendering of the colour as Dwight's demonstration shows. If the lights are set wrongly, in terms of the time of day, cloud cover, artificial light, etc, a truly distorted vision of the final building colours can be created.

Re: Matching Paint RGB Values

Dwight — Sun, 27 Jan 2008 01:21:19 GMT

Don't think that I missed your comment - this is different.

I appreciate the fact that the sun is yellow - never white [except in Lower Hutt, NZ] and that the sky adds blue in any lively scene. Rendering with white light inevitably makes dull imagery. The most accurate rendering color is achieved when the blue and yellow are neutrally balanced.

Getting the light "right" is essential, but, instead, my point addresses material making and how improper reflection settings unexpectedly alter a material's color. Furthermore, ignoring this aspect of material color wastes the effort of getting the RGB values to start with.

Lighting color aside, the reflectivity of materials is what determines their final color - in a rendering.

Those five boxes rendered are the same RGB color and in the same light. They appear to have radically different colors because i altered each light reflection amount. These reflectivities must be adjusted for each new material since they address specific behavior. When making materials, have you been ignoring the ambient, diffuse and specular reflectivity of your surfaces?

Re: Matching Paint RGB Values

Anonymous — Sun, 27 Jan 2008 01:41:57 GMT

Sorry I missed your point. Of course the reflectivity is of significant importance too. I always spend considerable time tweaking ambient, diffuse and specular reflectivity features of surfaces.

However it doesn't detract from the point of this posting that it is great to finally have RGB values for colours. This is a significant advancement from the paint manufactures in our country in my opinion and will assist architects.

Re: Matching Paint RGB Values

Dwight — Sun, 27 Jan 2008 02:20:11 GMT

I only waded into this discussion to dash the naive and false hope that simply having the RGB value results in accurate color.
There's plenty of work to do after that or tears will result.

Re: Matching Paint RGB Values

Djordje — Tue, 29 Jan 2008 17:13:24 GMT

Graeme wrote:
I cant find the RAL Add On since ArchiCAD 9? The Goodies folder is no longer in the AC11 folder. Has it been placed elsewhere or is it a special Add On from elsewhere?

Check Goodies in your Help ...

Re: Matching Paint RGB Values

Anonymous — Sat, 02 Feb 2008 11:11:53 GMT

Djordje,

Thanks for that info but can you be more specific please. I can't find RAL Add On in the Goodies folder in the Help menu. There is Profiler, Accessories, etc but I cannot find RAL.

Reflectance Values

The Resene and Dulux sites give Light Reflectance Values for paint colours but I am not sure how they relate to Ambient, Diffuse, Specular, and Mirror in Archicad? The paint websites only give one LRV as shown in the following excerpt from the Resene site. Any ideas? Thanks.

Re: Matching Paint RGB Values

Ralph Wessel — Sat, 02 Feb 2008 13:36:51 GMT

Dwight wrote:
I only waded into this discussion to dash the naive and false hope that simply having the RGB value results in accurate color.
There's plenty of work to do after that or tears will result.

How true - this is an unbelievably complex subject. I hit the same problems in publishing too. Many printers will only accept colour specs in CMYK because they don't want to be responsible for deciding how they should be converted from RGB - in many cases there is no direct correlation, i.e. there is no CMYK equivalent to a specific RGB value.

Re: Matching Paint RGB Values

Dwight — Sat, 02 Feb 2008 17:23:20 GMT

Observing that printing ink defined in CMYK cannot represent as many colors as light rays defined in RGB can is correct and a concern to offset printing houses accustomed to the outrageous requirements of advertising agencies attempting to match a difficult Pantone spot color. After that, the quiet reason of architects merely wishing to define 1000 different greys is simple.

MY angle on this is that accuracy or inaccuracy aside, having the RGB is just the start of defining a material. Take paint, for example. You want to show paint on your surfaces, and those surfaces will be sprayed, brushed or rolled, the paint will be eggshell, glossy or semi-glossy, it will have surfactants that automatically level it or not.

These qualities affect the observed color because the unpublished values - how the paint surface reflects light - TOTALLY destroys the usefulness of and false confidence provided by the manufacturer's RGB. If you have to guess at the diffuse, ambient and specular reflectivity of the surface, you might as well just guess at the RGB, too.

And DON'T get me started on metamerism or I will have to tell the story of visiting a light test room of a Mexican car seat manufacturer watching a team compare light falling on an expanded vinyl seat side versus its leather seating surface as seen at sunset when a driver opens his door and sees that the two don't match like they did at noon. He then goes angrily back to the dealership to learn that even though the leather interior on his Explorer cost an extra $1800. it was only the actual parts of the seat he sits against that were cowhide [more-or-less, seeing as how your cheaper cars only have acrylic-impregnated hide costing only slightly more than vinyl or fabric and not properly tanned leather like in your Bentley] and the rest was lousy, ordinary vinyl.

This, already, after the outraged owner, being from New Mexico and him having worn a new fringed buckskin jacket and the ochre dye from the buckskin fringes transferring to the beige seat back from being ground repeatedly against that seat back by his broad, manly shoulders and Ford already rolling over once and replacing the seat under warranty.

You can't blame that on metamerism.