Convert Colour SpacesConverting a colour value from one colour space to another is fairly easy. A colour value usuallylooks like a series of numbers separated by a comma. Arbitrary examples are: 123,234,21 (for RGB)or 34,23,1,67 (for CMYK) or 120,12,18 (for HSL). Colour values can also be hexadecimal, e.g. #12E19Fand may also be given a name (“MediumSpringGreen”). To convert a colour value, you need to know the colour space. Choose the correct colour space fromthe option menu on the Convert tab and enter the value in the field next to the option menu. Pressthe enter key or the return key and all values appear in the list. If you don’t know the name or value of the colour, then you can choose a colour from the Color Picker.The Color Picker can be accessed by clicking the little button at the bottom of the window. Thisbutton is labelled “Color Picker”. When you click on the Color Picker button, the color chooser of your operating system appears onthe screen. Choose any colour you like and close the color chooser. After the Color Picker closes, the Convert tab shows the values for the selected colour in all colourspaces. To use one of the colour values in your website or software, you need to copy the colour value andpaste it in its destination. You can copy every colour value by selecting it with the mouse andchoosing Copy from the Edit menu or by pressing Control-C (Command-C on the Mac).
At the top of the Color Names tab, there is a filter field. Color Converter will search for all colours that contain the string in the filter field. For example, if you type “light”, Color Converter displays all colours containing “light”, from LightBlue until LightYellow4. If you enter “blue”, it will find AliceBlue, but also Blue, BlueViolet, PowderBlue and DeepSkyBlue4.Clicking on a colour name sets the colour of the Color Picker to that colour. This means that the Convert tab will also display the value of that colour in all colour spaces. From there, you can copy the colour name. Naturally, you can also copy the colour name from the Convert tab and paste it into the filter field on the Color Names tab. The Color Names list follows a standard, which adheres to an old Unix tradition. These color names are used by the X11 window system and have been adopted by many Linux flavours and their window systems. You can find more about it on Wikipedia.
Create and Use the Histogram
To create a histogram, drag a picture file into the Histogram tab of Color Converter. The histogramwill be created automatically.You can also click on the Select button and select any area of your main screen. The histogram is created by examining a sample of the pixels of a picture. The RGB values are projectedin the cube below. Since RGB values contain three values, one for red, one for green and one forblue, the pixels can be ordered along the axes of the cube. The result is a cloud of points insidethe cube. The cube is divided into 8 areas. Each area is tangent with one of the following colours: black,red, green, blue, cyan, magenta, yellow, and white. Now we count the number of points in each area.The resulting numbers are depicted in the histogram. From the histogram, you can read which colours dominate your picture. Sometimes, a picture may seemmostly yellow but actually appears to be more green. This can have many causes, such as the colourprofile being used, your screen settings, or a form of visual deception. Colour blindness may havean effect too –not all forms of colour blindness are always recognised as such! When you know which colours dominate your picture, you can decide which pictures may match the pictureto create a collection that’s pleasing to the eye, or you can decide on the colours for your webdesign.
To resize a picture, drag your picture file into the Resize tab of Color Converter. Be careful toavoid the text fields. The file will be created automatically, next to the original file, with “resized”in the name. You can also drop multiple picture files or even an entire folder onto the Resize tab.You can also use the Resize… button to select on or more files or a folder. To determine whetherthe Resize… button lets you select a file or a folder, you need to choose the correct option inthe option menu button labelled Input. Optionally, you can choose a particular format from the Outputoption menu button. The height and width values are the dimensions of the rectangle within which you want to fit yourpicture. If you have a picture of 1000 pixels wide and 700 pixels high and you want to fit it ina rectangle of 500×500, then your new picture will be 500 pixels wide and 350 pixels high. ColorConverter makes sure that the relative dimensions (also called aspect ratio) of your picture stayunchanged.
Colour Channel Separation
To separate the colour channels of a picture or to convert the picture to grayscale, drag your picturefile into the Filter tab of Color Converter. Press the Convert button to start the conversion. Thiswill take a few seconds and progress is displayed in the progress bar at the bottom of the window.If you choose a colour from the Filter menu button, Color Converter will take the RGB values ofthe picture, copy the relevant value (either red, green or blue) and set the other values to 0.If you choose the gray filter, Color Converter will calculate the average brightness from the threecolour values and set all three RGB values to the same average value. To speed up conversion if you want to convert many files at once, you can turn of the Preview option.Without this option, the previews will not load, which saves some time. If you are going to dropmany pictures onto the Color Converter window one by one, then you probably will want to turn onAutomatically, which saves you the trouble of clicking on the Convert button.