RGB colour numbers

[bootneck]

Whilst making a few decals recently, for an aircraft in a group build, I noticed when I am filling in the colours that there are three colour ranges; for Red, Green and Blue.  They range from 0 to 255 and, depending on the mix of numbers, they give me a decent choice in colour range, although it is all very much by eye.  I would like to get the colours to be more accurate, for example;  dark sea grey on a Wildcat/Martlet,  or PRU blue on a Spitfire etc.  Is there a 'modellers' guide or database that gives such numbers to match aircraft paint colours?

 

For example: Here is a view of a PBY-5 Canso with bright yellow livery

 

 

Here, the yellow colour is being chosen for the decal on the nose of the fuselage, with black and white 714 over it.  Note the RGB colours, circled in red, show 255, 251, 60 respectively,  but this is just guesswork and done by adjusting the numbers randomly until it looks right.

 

 

When the decals are applied on the model, the yellow is a near match  but just not accurate enough; hence my query whether there is a 'modellers' reference for RGB colours?

 

cheers

Mike

[xffw45343tg]

One thing you can do is open up your picture/photo in windows paint and use the "dropper" icon to "suck up" the colour in a particular area, making it the active brush colour. You can then look at this colour's properties and it will give you the RGB value.

There's lots of fascinating info on Wikipedia about RGB, CMYK and all the related colour/dye/light technologies.

 

Kirk

[bhouse]

Kirk mentioned RGB and CMYK. These are the methods used for describing colour on screen that emits light (RGB) and on a surface that reflects light (CMYK)

RGB is red, green and blue - to match the way a computer or TV screen produces colour. CMYK is Cyan, Magenta, Yellow, blacK - to match the way a printer makes different colours.

If you're trying to produce decals, I suggest you set your drawing/design programme to CMYK mode. How you do that depends on the programme you're using.

There's a page here that shows the CMYK equivalents for variousmilitary schemes.

For colours such as those on your Catalina, I think Kirk's suggestion of importing an image shot under 'neutral' () light into your graphics programme and sampling the colour using the eyedropper is a good place to start. Experimentation with subtle changes will be called for, I suspect.

Brian

[xffw45343tg]

Brian is clearly in a league above me when it comes to this subject (my experience is largely from supporting the configuration of a Product Lifecycle Management tool for a UK retailer & working with the Colour Technologists there) but I'll support the whole can of worms lighting thing - the technologists have standardised light sources for illuminating various materials & fabrics when sampling colours. The same colour has a different recipe depending on the substrate on which is being printed...

 

As it impacts the display of your fuselage yellows on my screen, if I sample a couple of adjacent pixels in Paint and then used "Edit Colour" to see the RGBs for the screen, I get 233, 190,96 for a bit just out of direct daylight and 233,186,147 for an area just slightly shaded. 

 

Is it beginning to look like a mass escape at the wormery yet?

 

Kirk

[bootneck]

Thanks Brian and Kirk.  I don't seem to have the ability to select CYMK references but the eye-dropper shows RGB.  The reference shows 223, 178, 89 which is similar to those that Kirk found; unfortunately, whilst the colour looks good on screen, it does print a much browner shade on paper.

 

Thanks for the link Brian, that looks as if it is going to be really useful.

 

I am using Inkscape to draw the decals and PhotoImpact for the photo viewing.

 

cheers

 

Mike

EDIT:  I've found the CYMK in Inkscape, just don't know how to get it with an eye-dropper in my program... yet.

[xffw45343tg]

Get yourself a head full of this. As Brian correctly pulled me up on, the RGB values are only any good for defining display of light from a screen, not the reflection of colours from a surface. I suspect that Inkscape may have the necessary tools to establish the most appropriate CMYK.

 

[Jamie @ Sovereign Hobbies]

As a paint makist, I'll toss in that CMYK is worthless for this also.

 

Just as RGB is only useful when trying to light up pixels, CMYK is only intended for blending inks. Inks and paint pigments behave rather differently. The fact of the matter is that any kind of digital sampling is fraught with danger because as Kirk said above, you have no control over either the lighting source, the viewing angle nor the colour balance of the device that recorded the image.

 

Real paint companies use the CIELAB colourspace. Real colour measurements are taken from a calibrated temperature of light source and the sample is consistently viewed from a specific angle relative to the light source. This is to ensure that light refraction from the sample is consistent and the wavelengths observed are the effects of the colour being viewed and not differences in glare or colour from the light source.

 

There are numerous online sites that allow you to convert between spaces.

 

If you only want to look up colours based on RGB values to find something close, you can use www.e-paint.co.uk for that. But, you'll get hundreds of different sets of results from sampling different pixels all over that photograph.

[mollythedog]

I hope I am not stating the obvious here,but might a slightly different approach work? Rather than getting too tied up on RGB/CMYK just use whatever program you are using to make as many small (say 20mm square) swatch boxes,and fill them with various "mixes" of your preferred colours,and then print off the whole sheet, onto your usual decal paper,using your usual settings-in fact treat it like a decal,even varnishing it after if using inkjet,to get the actual colour of each printed swatch. You do not of course have to do a whole sheet, across the top of an A4 sheet in one line or as many samples as you require. I have used this technique many times when trying to find the exact shade I want,and I keep them for future reference,much like a colour paint chart.  If your program allows text then label each swatch as you drop the colour into it and this will print with the rest,giving you instant reference to actual  colours that you will get from your current printer on your usual settings.  Works for me.....

[Giorgio N]

Jamie's suggestion of using e-paint.co.uk is a good one, however even with this the correspondances are not always that great. I tried a while ago to print a set of swatches for some common FS colours using their equivalents, then compared these to modelling paints and to pictures of the real things... most correspondances were not good.

I have to say that greys are not easy to print well and the kind of blue-greys used in modern camo schemes are maybe even worse, in any case I would only use those correspondances to get in the right ballpark and then adjust the colour as necessary.

Your result in any case does not look that bad, the yellow is indeed a bit lighter but you may be able to blend in the colour using a small brush, the original yellow paint and a lot of patience....

 

[Jamie @ Sovereign Hobbies]

Printers are fairly hopeless, but maybe we shouldn't be so hard on them.

 

Or, in otherwords, the smallest batch of paint our paint machines can make is 1 litre. Of that, a maximum of 100ml of pigment can go in (or bad things happen I won't describe here). That 100ml of pigment is the minimum total batch size that this equipment (many ££££'s worth) can be certain to inject the different colourants in accurate enough proportions to each other to achieve the desired shade.

 

Is that relevant? Well, yes.

 

When we print the computer converts to CMYK to give the printer proportions of Cyan, Magenta, Yellow and KBlack inks. The computer can't control who made the inks and whether each colour has consistent staining power from one brand to the next. There's also no feedback loop to the computer to tell it what colour it really achieved - so from the outset the computer can only come up with a CMYK ratio for what someone has told it should achieve a resultant colour providing each colour of ink performs as expected.

 

As if that weren't bad enough, we expect a machine to be able to meter out absolutely miniscule quantities of these inks in the correct proportions to achieve a target colour. If the ££££'s professional paint mixing desks need a comparatively huge 100ml total puddle of colour to get the % errors in metering each component colour down low enough to be sure the colour is repeatable, how can we really expect a printer - even a big expensive publisher's printer - to achieve the same colour accuracy metering out such tiny quantities as to merely coat 1/360,000th of a square inch dots of paper and achieve the right colour?

[bootneck]

2 hours ago, mollythedog said:

I hope I am not stating the obvious here,but might a slightly different approach work? Rather than getting too tied up on RGB/CMYK just use whatever program you are using to make as many small (say 20mm square) swatch boxes,and fill them with various "mixes" of your preferred colours,and then print off the whole sheet, onto your usual decal paper,using your usual settings-in fact treat it like a decal,even varnishing it after if using inkjet,to get the actual colour of each printed swatch. You do not of course have to do a whole sheet, across the top of an A4 sheet in one line or as many samples as you require. I have used this technique many times when trying to find the exact shade I want,and I keep them for future reference,much like a colour paint chart.  If your program allows text then label each swatch as you drop the colour into it and this will print with the rest,giving you instant reference to actual  colours that you will get from your current printer on your usual settings.  Works for me.....

Not the obvious at all and it is something that I had not thought of.  Thanks for the example swatches you emailed.  Interestingly, I have done this many times with actual paint; by painting individual swatches onto plastic sheet, and then coating them in Klear etc., so why hadn't I thought of that for the PC/printer?

 

Lesson learned!

 

Mike

[bhouse]

There's a wealth of interesting information popping up on this thread. It was good to hear from @Jamie @ Sovereign Hobbies as he really ought to know! 

 

My experience in the field is as maker of videos, where I have had to endure many years of clients complaining that the colour of their logo in a video does not match the one on their brochure - usually demonstrated by pointing angrily at the logo while holding it up next to their LCD laptop screen showing the video. 

 

And the points made above are so true. If you sample a 'solid' colour at 100 different spots on a photo, you'll get 100 different readings. It's not just random variation though. As @Kirk demonstrated, areas that are in shade will generally have a lot more blue than the same colour in direct sunlight.

 

I'll continue to read and learn!

Brian

[mollythedog]

I would not disagree with anything that has been said here regarding light/angles/paint/photos/videos and a myriad of other things,but as the OP wanted to print a decal onto decal paper and match it (I use that term as loosely as you want) to a painted model then in the end,sampling colours from your printer onto the actual paper is the quickest,easiest and most direct way i can think of. If anyone else has a better solution I'd love to hear it. It will never be perfect,though I'd admit the professional decal printers (that use an entirely different process) probably could do it fairly easily.  I'll stick to my £30 Canon Pixma that gives me very good results,and wish you all luck with your endeavours. 

 

mtd