最近看到了这篇文章 很有意思 能不能用这个来实现 用户自定义的网站风格呢 有时间做个试验
Not coming from a graphics based background my method may not be the best solution, but it seems to work just fine.
To apply a color wash a base RGB color value is decided upon as a reference point and an adjustment value calculated for the color wash’s RGB value to be applied. This adjustment is calculated for each of the red, green and blue components. Once this is done each of the image’s pixel’s red, green and blue components is adjusted by the calculated amount to produce the color wash.
Each of the RGB components of a color can be represented by values from 0 to 255, so taking the mid point of 127 as the base reference point and taking the desired RGB component values of the color wash to apply we can calculate the adjustments to be made to each pixel.
Adjusting red, green and blue component values can sometimes result in a value outside the allowed range of 0 to 255; in these cases we compromise and simply use the minimum or maximum value allowed as appropriate.
The table below illustrates how values are adjusted:
| Hex Value | Red | Green | Blue | Color | ||
| Base Color | 7F7F7F | 127 | 127 | 127 |
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| Color Wash To Apply | 1280AA | 18 | 128 | 170 |
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| Adjustment Value To Use | 18 – 127 = -109 | 128 – 127 = 1 | 170 – 127 = 43 | |||
| Example Pixel 1 Original Color | A5A5A5 | 165 | 165 | 165 |
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| Example Pixel 1 Washed Color | 38A6D0 | 165 – 109 = 56 | 165 + 1 = 166 | 165 + 43 = 208 |
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| Example Pixel 2 Original Color | 545454 | 84 | 84 | 84 |
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| Example Pixel 2 Washed Color | 00557F | 84 – 109 = -25 = 0 * | 84 + 1 = 85 | 84 + 43 = 127 |
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| Example Pixel 3 Original Color | 2E2E2E | 46 | 46 | 46 |
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| Example Pixel 3 Washed Color | 002F59 | 46 – 109 = -63 = 0 * | 46 + 1 = 47 | 46 + 43 = 89 |
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Using the Code
To use this functionality in your projects simply download the source files accompanying this article, drop GavDev.Image.dll into the bin directory of your project then make a reference to the class library GavDev.Image.dll. There’s two interfaces provided for your convenience:
The first interface accepts individual red, green and blue values:
ColorWashImage(ByVal FilePathOriginal As String,
ByVal FilePathNew As String,
ByVal Red As Integer,
ByVal Green As Integer,
ByVal Blue As Integer,
Optional ByVal Quality As Integer = 100,
Optional ByVal Encoding As String = "image/jpeg")
The second interface allows you to pass a single combined 6 digit hexadecimal RGB value in as the color wash value:
ColorWashImage(ByVal FilePathOriginal As String,
ByVal FilePathNew As String,
ByVal HexRGBValue As String,
Optional ByVal Quality As Integer = 100,
Optional ByVal Encoding As String = "image/jpeg")
Both interfaces expect parameters FilePathOriginal, the physical location of the original grayscale image and FilePathNew, the physical location to save the resulting color washed image. Optional parameters are also present to dictate the quality and encoding of the output images.
Below is an example of the class being used as it is in the accompanying demo project:
GavDev.Image.Manipulate.ColorWashImage(Server.MapPath("Images/Gav.jpg"),
Server.MapPath("Images/Gav." & txtColorWash.Text & ".jpg"),
txtColorWash.Text)