Colour Matching

[Colin Bernard]

I recently dug out my Jamara Marchetti kit from my pile of waiting projects. I have always liked the looks of this aircraft which you may remember attacking Bond's DC-3 in 'Quantum of Solace'.

The decision then was which plane to model for colour scheme. There are many around, but I decided on D-EDUR...

Interesting looking livery, but once I started the covering I realised it was a poor choice for modelling owing to all the sponsor logos.

No problem in finding and generating the logos, but the issue was that a lot of these involve white print - and you cannot print white. (A lot of people don't realise that - but when you print white on a normal printer, the printer simply doesn't print so allowing the white paper to show.)

No problem - I have white decal paper. But then we have another problem in that the logos need to have the background camouflage showing through.

The answer was to copy the background onto the actual decal so it could be overlaid.

This introduced a new challenge of how to get the computer to generate colours matching those on the model.

The next few posts show how I solved this.

[Colin Bernard]

So I use a combination of MS Paint and Word to generate my decals and Paint allows you to define any colour.

For those of you who are unaware, generally on PCs colours are defined by the level of Red, Green and Blue using values of 0 to 255 for each. White is 255,255,255 for the 3 colours and black is 0,0,0. (Other schemes such as HSV/HSL are also used but I stick to RGB initially.

For those with artistic bones, then you can go straight into the Paint colour editor and mix in the colours as required...

For myself I have great trouble in deciding what colours are required so I needed help and found a great program for my phone - Color Grab. (This is an Android app, but I guess there are similar for the iPhone.)

With this you can use your phone's camera to scan a colour...

Which will then give you a palette with the necessary RGB values...

 

Edited By Colin Bernard on 03/09/2017 14:28:30

[Colin Bernard]

So far so good - we have RGB values that we can plug into a PC - but printing these out does not give us a match due to a number of variables...

i) The camera response

ii) The printer output

iii) The paper used

For the first we cannot do much about that but for ii) and ii) always use the photo enhance options on photo paper.

So now we have colours near to the match - but unless you are very lucky they will not be exact and we need to tweak the colours - but this could take forever as you change each RGB value, reprint, test, change RGB etc

So I developed a tool in Excel to come up with colour swatches so the matching process is a lot more efficient.

The spreadsheet is shown below and has 4 sections, each section having 4 columns 1 each for the 3 RGB values and the 4th the resulting colour.

The top two rows hold the initial RGB values (seed), and the increment to be applied to each. When entered all the rest of the RGB values will be calculated. Once each of the 4 sections has been entered for the top 2 rows, then clicking the 'Update Colours' button will generate the actual colour blocks...

Negative values can be used for the increments so the effect of having less of a colour can be tested. Making colours lighter or darker is achieved by using positive or negative values across all colours as shown in the above example.

Once happy, then it is printed out and the swatches cut along the dotted lines for easy matching...

[Colin Bernard]

The final result is a reasonably matched set of decals...

which can then be used on the final model...

which I hope you agree is reasonably close to the plane in the first post.

If you want the Excel I have shared it here. Note that it does use a macro so Excel will ask you for approval to run it and I recommend you run it on your PC rather than using Excel online.

Hope this helps!

Edited By Colin Bernard on 03/09/2017 14:46:24

[Stevo]

I looked at the excel version and it deletes the Button

I also downloaded it and also the button was missing (OK, so I know Excel VBA and can create my own...)

Just for info

[Colin Bernard]

Hi Stevo - Have just taken the link and taken the 'Edit in Excel' option from the 'Edit Workbook' link and it opened fine, complete with button, so not sure what is going on.

It may be a security issue with Excel online, so here is another link that takes you to the folder where the file can be downloaded directly.

[Colin Bernard]

Just realised that there are two ways of downloading from the first link I gave, where the file is opened in Excel online.

Excel online does not support controls (buttons) which is why you need to open the file on your PC - but to do this you need to take the 'Edit in Excel' link as described above.

If you take the 'Download' option from the options menu (the 3 dots at the right hand end of the Excel online menu bar), then the downloaded version is the same as the Excel online version, i.e. no controls.

[Stevo]

Oh...

Runtime error 1004

Application-defined or object-defined error

Looking at the debug it's the Cells(Row, Col).Interior.Color = RGB(R, G, B) that it doesn't like for some reason ...

[Stevo]

DoHHH!!!!

You've protected the workbook... All works now I've taken that off     

 

Edited By Stevo on 03/09/2017 16:15:08

[Colin Bernard]

Unprotected version now uploaded. Only edit the coloured cells!