Solved

RGB model

Posted on 1998-03-17
5
463 Views
Last Modified: 2012-05-04
I wanted to know what relation betwen red, blue and green in the RGB model gives me all the variety (density) for the blue color (cyan, solid blue,....)
0
Comment
Question by:ciri
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 3
  • 2
5 Comments
 
LVL 2

Expert Comment

by:EbenBrooks
ID: 1112265
I'm not sure what you mean for "all the variety," because there are a great number of shades of blue between Cyan (R0,G255,B255) and Purple (R255,G0,B255). A pure blue would be R0,G0,B255), and a dark blue would be R0,G0,B127. What precisely are you looking for?
0
 

Author Comment

by:ciri
ID: 1112266
I would like to get all the shades of blue (including the extremes: cyan purple, pure blue...). I hope it was possible using an equation that connect all the variables (red, blue and green). I have an application that loads an image. In this image I want to distinguish the portions in blue, but not a concrete blue (I want all the shades of blue). If I set in this variables, for example, R0, G255 and B255, I only see Cyan. My code is (in C) like the following:

  for(y=0;y<heigth(image);y++)
  {                                                     //two sentences "for" cover all the image
       for(x=0;x<width(image);x++)
      {
           if ((pLine[x*4+RGBA_RED] == 0)
              &&(pLine[x*4+RGBA_GREEN] ==255)
              &&(pLine[x*4+RGBA_BLUE] == 255)) //cyan
          {
                                       //show this pixel
                                      //with this code I only show cyan
                                     // i want a relation tha let me show all the shades of blue
                      }
      }
  }

Thanks.
0
 

Author Comment

by:ciri
ID: 1112267
Adjusted points to 60
0
 
LVL 2

Accepted Solution

by:
EbenBrooks earned 60 total points
ID: 1112268
Oh! I see what you mean.

For a color to fall into the range you specified, the value of Blue must always be equal to or greater than the values of Red and/or Green. If Blue is equal to the value of either Green or Red, then it CANNOT be equal to the other!

For instance: R254, G254, B255 is a shade of blue. It's very, very close to white, and may be indistinguishable by the human eye. At the same time, R254, G255, B255 is a shade of cyan of similar brightness.

If you want to make sure you're only including the values of blue that are distingushable as blue to the human eye, do this:

The value of Blue must be equal to or greater than the values of Red and/or Green.

If the value of Blue is equal to the value of either Red or Green, then the value of the other (Red or Green) must be 20-30 points below the value of Blue.

This should give you all the visible values of blue.

Hope this helps!

--Eben
0
 

Author Comment

by:ciri
ID: 1112269
Your answer is excellent!!
0

Featured Post

Free Tool: SSL Checker

Scans your site and returns information about your SSL implementation and certificate. Helpful for debugging and validating your SSL configuration.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Many programs have tried to outwit PowerPoint in terms of technology and skill. These programs, however, still lack several characteristics that PowerPoint has possessed from the start. Here's why PowerPoint replacements won't entirely work for desi…
Technology opened people to different means of presenting information, but PowerPoint remains to be above competition. Know why PPT still works today.
In this tutorial viewers will learn how to create blended and gradiated shapes in Illustrator using the blend tool Draw two shapes, one of them in a different color: Select both and create a blend by going to Object > Blend > Make: Blends can also b…
Learn how to set up basic frames and paths in Prezi and understand the open space that Prezi allows you to create presentations in.

635 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question