purpose of dividing saturation / 50 and hue / 50?

Question

i am controlling the hue and saturation of the backcolor of the form with scrollbars:

Private Sub tbHUE_Scroll(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles tbHue.Scroll
        Dim r, g, b As Integer
        HSVtoRGB(r, g, b, tbHue.Value, tbSaturation.Value / 50, 255)
        Form1.BackColor = Color.FromArgb(r, g, b)
        Label1.Text = tbHue.Value


    End Sub
    Private Sub tbsaturation_Scroll(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles tbSaturation.Scroll
        Dim r, g, b As Integer
        HSVtoRGB(r, g, b, tbHue.Value, tbSaturation.Value / 50, 255)
        Form1.BackColor = Color.FromArgb(r, g, b)
        Label2.Text = tbSaturation.Value
    End Sub

i would like to know what is the purpose of dividing by 50?

Answer 1

It's hard to know what the person was thinking that did that division, but the result is that you will get a color that's less "pure" (has more white mixed in).

For more info you may want to look at the conversion algorithm, which has good comments as well.

Answer 2

If you're referring to this question: http://stackoverflow.com/questions/1048892/implementing-a-trackbar-that-will-change-background-color-of-form, the HSVtoRGB procedure expects:

• a saturation value between 0.0 and 1.0
• a value value between 0.0 and 1.0
• a hue value between 0 and 360

This is in-line with the intent of the algorithm, as it points to the wikipedia version as its reference, at http://www.xtremevbtalk.com/showthread.php?t=302304. I didn't proofread the implementation to check for correctness though.

Dividing the saturation value you get from the tbSaturation textbox by 50 allows you to interpret values between 0 and 50 entered by the user. You might actually want to divide by 100 instead to allow a 0-100 range.

Answer 3

That depends on the range of your scroll bars and the intended range of HSVtoRGB.

Without greater context, I'd assume that your scroll bars are ranged from 0 to 50 and that the code is attempting normalize the values or they're trying to scale the components.