Presentation on theme: "1/30 Saturation And Value Modulation: A New Method For Integrating Colour And Grey-Scale Imagery David Viljoen & Jeff Harris Geological Survey of Canada."— Presentation transcript:
1/30 Saturation And Value Modulation: A New Method For Integrating Colour And Grey-Scale Imagery David Viljoen & Jeff Harris Geological Survey of Canada
3/30 Integrating Colour & Grey-scale imagery Enhancing the visualization of a dataset. DEM with shaded relief of DEM for Mt. Logan }
4/30 Integrating Colour & Grey-scale imagery Visualizing the relationships between two datasets. } K-Th-U (RGB) Gamma ray spectrometer with Landsat TM 7
5/30 Layer transparency 20% 40% 60% 80% 60% 40% 20% Transparency of Colour (Colour over shaded relief) Transparency of shaded relief (Shaded relief over colour) Layer transparency control in ArcMap Result is independent of layer order
6/30 Red-Green-Blue coordinates RGB used to define colours in computers and image files. Integrating colour and grey scale imagery involves manipulation of colours in RGB & HSV coordinate spaces.
7/30 Hue–Sat–Value coordinates Hue Value V = 100 S = 100 0º0º 120º 240º º0º 359º Saturation Hue
8/30 Conventional Value Replacement R G B H S V R G B RGB2HSVHSV2RGB STOP
9/30 Problems with Value Replacement Loss/corruption of colour where: 1.Pixel colour is differentiated on Value (HSV) 2.Pixel colour has low saturation (achromatic axis of RGB cube)
10/30 Problems with Value Replacement 1. Pixel colour is differentiated on Value R,G,BH,S,V 0,110,0120,99,43 0,188,0120,99,74 0,253,0120,99,99 Replace V with pixel values from shaded relief
11/30 Problems with Value Replacement 2.Pixel colour has low saturation (achromatic axis of RGB cube) … to replace the Values of colours with low saturation … Using Values from grey-scale image … … results in poor image integration.
12/30 Conventional RGB Modulation R G B R’ G’ B’ Multiply
13/30 Problem with RGB Modulation Overwhelming majority of pixels in the output raster will have a darker colour than original. Better than value replacement. Colours are not “lost” but what happened to the yellow.
14/30 Inspiration for SatValMod
15/30 SatValMod Concept Lower Saturation Cutoff Lower Value
16/30 SatValMod Multipliers Lower Saturation Lower Value Cutoff Value multiplier Saturation multiplier Shade value Multiplier
17/30 SatValMod Detail H S V R G B * * = = Pixel value in grey-scale image determines multiplier Sm Vm HSV2RGB Multipliers
18/30 SatValMod in ArcGIS SatValMod written in VBA Runs in ArcGIS 8.x or 9.x (ArcMap – ArcView or ArcInfo)
19/30 SatValMod Colour Raster Options CLR file pixel value and RGB’s R G B 8-bit image planes 3 separate 8-bit raster files R G B
20/30 SatValMod Parameters
21/30 SatValMod parameters (CutOff) CutOff = 255CutOff = 180CutOff = 128 CutOff should be the maxima of the shade raster histogram. For shaded relief images, this is sin(Altitude).
22/30 SatValMod parameters (Vmin) Vmin = 0Vmin = 0.3Vmin = 0.6 Vmin > 0 is best so shadows are not completely black.
23/30 SatValMod parameters (Vexp) Vexp = 0.3Vexp = 1Vexp = 3 Vexp 1 is recommended so shadows are not too extensive.
24/30 SatValMod parameters (Smin) Smin = 0Smin = 0.3Smin = 0.6 Smin < 0.4 is recommended. Higher values do not provide enough decrease in saturation.
26/30 Geology + Shaded relief aeromag. Value replacementSatValModRGB Modulation SatValMod does not lose or corrupt original colours.
27/30 Pan sharpening Value replacementSatValModRGB Modulation Colour critical? Use SatValMod. Sharpening critical, colour unimportant? Use value replacement
28/30 Ternary images Value replacementSatValModRGB Modulation U-Th-K RGB composite image integrated with shaded relief DEM
29/30 Conclusions Value replacementSatValModRGB Modulation SatValMod provides better integration of colour and grey-scale imagery compared to many traditional methods. Colour is more accurate. SVM Parameters provide flexibility on integration.
30/30 Availability ArcGIS 8.x and 9.x MXD VBA ArcMap –ArcView or ArcInfo for download instructions