12 mhj/ Optimal Color Representation of Multi Spectral Data M.L.H. van Driel s Supervisors: P. Sereda Prof. B.M. ter Haar Romeny

12 mhj/ Contents Introduction Artherosclerotic plaques Color Models –RGB –HSV –CIE Lab Methods & Results Conclusions Discussion Recommendations

12 mhj/ Introduction From gray scale to multi spectral color images should improve the possibilities for tissue recognition and classification. Examples are multi spectral MRI measurements for artherosclerotic plaque classifications in medium and large arteries.

12 mhj/ S.v.d.Ven (2004)4 Artherosclerotic plaques Stable – Vulnerable Important tissues –Calcification –Fibrous tissue –Hemorrhage –Lipid –Lumen

12 mhj/ Color Models RGB (Red Green Blue) HSV (Hue Saturation Value) CIE Lab (Commission Internationale d`Eclaraige Lab)

12 mhj/ http:// kshop.html 6 Color Models - RGB Primary colors Range (0-1) Device dependant

12 mhj/ http:// s/colormodels/color_models2.html 7 Color Models - HSV Hue: color Saturation: dominance of hue Value: lightness – darkness Range (0-1)

12 mhj/ http:// /q3-21.htm 8 Color Models – CIE Lab L – Lightness (0-100) a – green red (-/+100) b – blue yellow (-/+100) Device independent Difference between 2 colors in the Lab space is an indication of the contrast

12 mhj/ Methods & Results Input –Matching –Histogram Equalization The Optimal Color Model and Configuration

12 mhj/ Methods & Results - Input 8 sets of 5 images with 3 tissues classified –T1 weighted (2D) TSE (1) –PD weighted TSE(2) –T1 weighted (3D) TFE(3) –Partial T2 weighted TSE(4) –T2 weighted TSE(5)

12 mhj/ Methods & Results - input Matching –Same regions in different images should have the same locations Histogram Equalizing

12 mhj/ * _convert.html 12 Methods & Results – The Optimal Color Model and Configuration Comparing the different Color Models –Converting RGB and HSV to CIE Lab * Calculating the distances between the tissues

12 mhj/ Methods & Results – The Optimal Color Model and Configuration Red = CIE Lab Green = RGB Blue = HSV

12 mhj/ Methods & Results – The Optimal Color Model and Configuration Maximum of the minimal distance –Cut off 30

12 mhj/ Methods & Results – The Optimal Color Model and Configuration Good configurations? the configurations {{3,1,2},{3,2,1},{5,2,1},{5,1, 2}} were found within the boundary conditions in 7 out of 8 cases (all within the Lab Color Model)

12 mhj/ Conclusions To distinguish just arbitrary tissues CIE Lab is an appropriate Color Model In specific cases there can be better settings (in CIE Lab or even HSV) than in the arbitrary case RGB should not be considered an option

12 mhj/ Discussion No Golden Truth “Cut off 30” at least questionable Histogram Equalization? Other input

12 mhj/ Discussion Histogram Equalization Filters

12 mhj/ Discussion – other inputs

12 mhj/ Recommendations 5D instead of 3D input Differentiate for distinguishing different tissues Alternative for Histogram Equalization Other inputs

12 mhj/ Thanks Petr Sereda Bart ter Haar Romeny Woutjan Branderhorst Martin Knýř