This app can be used to create a spectrum curve with filled colors defined by wavelength in x data.
Download the file Color_Spectrum_Plot.opx, and then drag-and-drop onto the Origin workspace. An icon will appear in the Apps Gallery window.
- Make a worksheet for xy spectrum data or a graph window for spectrum curve active. Click the Color Spectrum Plot icon in the Apps Gallery window. Note that spectrum data's x should represent wavelength and its unit must be nm.
- A dialog will open. Check Smooth sRGB check box, colors for wavelength will be smoothed.
- Click OK button. A color spectrum plot will be created. Area between spectrum curve and x axis will be filled by colors defined by wavelength in x axis. And three columns for plot data are created in a worksheet. The third column includes RGB values for its wavelength in x data. Colors will be set missing values for wavelength outside the range 360nm to 830nm.
Sample OPJU File
This app provides a sample OPJU file. Right click on the Color Spectrum Plot icon in the Apps Gallery window, and choose Show Samples Folder from the short-cut menu. A folder will open. Drag-and-drop the project file ColorSpecPlotEx.opju.opju from the folder onto Origin. The Notes window in the project shows detailed steps.
Note: If you wish to save the OPJU after changing, it is recommended that you save to a different folder location (e.g. User Files Folder).
- Convert wavelength (unit: nm) to CIE 1931 XYZ
In the app's folder, CMF.csv file includes color matching functions (360nm - 830nm) for CIE 1931 2° Standard Observer. Use wavelength in x data to interpolate on color matching functions, and CIE 1931 XYZ values for each x can be calculated. XYZ will be set missing values for wavelength outside the range in the csv file.
- Convert XYZ to sRGB
CIE XYZ can be converted to RGB values by linear transformation.  D65 is used for the transformation in this app. Apply gamma correction, and RGB values can be transformed to sRGB. 
- Smooth sRGB
Follow the description in reference , RGB values are normalized, smoothed and corrected by gamma.
- Making Color Spectrum Plots