I am able to perform fusion of Landsat 8 (B5 B4 B3 as RGB) by upsampling 30m to 15 m and perform color transform(Brovey) . Then fusing R G bands of MSS with PAN stretched as B band. Fused image doesn't show valid reflectance values...i couldn't perform DN to reflectance conversion of PAN band.
http://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLI-B8/941/2016/isprs-archives-XLI-B8-941-2016.pdf
PLEASE CHECK THE FORMULA OF MERGING....TWO 3 OPTION ARE THERE IN ERDAS IMAGINE SUCH AS PCA, IHS ETC BASED MERGING.
You can calculate TOA reflectance of PAN band of L8 using band specific constant values and USGS formulae. After PAN sharpening, the spectral profile s of Sharpened images often get distorted because MS bands with 30 m spatial resolution changed into 15m after PAN sharpening. Hence, you should use sharpened image for visual interpretation only.
Answer I gave to a previous questions might be of interest to you:
How much the spectral information is impacted by pan sharpening is dependent on the method used; take look at the three papers below for examples of what I have used with various digital image data sets. Keep in mind, that if you are pan sharpening bands who's spectral window is outside the pan's spectral window then there is the possibility of 'edge reversals' that will impact the results (i.e., a boundary / line may be dark to light in the visible bands which includes the pan band BUT light to dark in the nir or swir bands so will be affected by the pan sharpening). Pay particular attention to the first paper / link:
Comparison of Three Different Methods to Merge Multiresolution and Multispectral Data: Landsat TM and SPOT Panchromatic (1991)
https://www.researchgate.net/publication/200458993_Comparison_of_Three_Different_Methods_to_Merge_Multiresolution_and_Multispectral_Data_Landsat_TM_and_SPOT_Panchromatic
Digital merging of Landsat TM and digitized NHAP data for 1: 24,000-scale image mapping((National High Altitude Program)) (1986)
https://www.researchgate.net/publication/240321338_Digital_merging_of_Landsat_TM_and_digitized_NHAP_data_for_1_24000-scale_image_mappingNational_High_Altitude_Program
An automatic optimum kernel-size selection technique for edge enhancement (1982)
https://www.researchgate.net/publication/223377841_An_automatic_optimum_kernel-size_selection_technique_for_edge_enhancement
Good luck with your work.
Pat
Article Comparison of Three Different Methods to Merge Multiresoluti...
Article Digital merging of Landsat TM and digitized NHAP data for 1:...
Article An automatic optimum kernel-size selection technique for edg...
I have doubt on one more output...pls see
1. Input 7 Band Landsat 8 image....performed radiometric calibration....DN values converted to reflectance ....i can see pixel values in the range 0.0 to 1.0
2. Since image is very large, i have taken spatial subset (141x135) of reflectance img.
3. Now to apply fusion...I have resized(upsampled this 30m spectral subset(RGB bands) to 15m) Now resized spatial subset is 280x269.
4. I have taken PAN bandof same Landsat 8 image and converted DN to reflectance (same process of radiometric calibration) and took spatial subset 280x269 . Reflectance values are in the range 0.0 to 1.0
5. For fusion , By taking input as resized RGB ( 3band MSS) and performed color transform RGB to HSV. Values are converted to DN (i can see 3 values of same location R G B in the range 0 to 255...they are no more in the range 0.0 to 1.0 i.e. reflectance values....
6. Then i have performed inverse transform HSV to RGB by taking H and S band from resized MSS and V band as PAN.
I didn't perform stretch data step on PAN band (since it has values in the range 0.0 to 1.0)
7. Then i have performed classification of fused image...
Is output of Step 5 correct..?
Is fused image correct...?
How do I chk whether fusion is producing correct image..?
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