Image Comparison
Sir Issac from India  [3 posts]
15 year
hi .. as such i am newbie to Roborealm which is just awesome ...

i ve just attached two pics below ..

i just want to compare dese two images and tell by colour which position have diff colours ...

by yes we can see dat the left bottom 2 colours only vary ..

how to go abt this using robo realm ..

ie .. .comparison of 2 images using colour bandwidth spectrum . a

Anonymous 15 year
can some pl suggest me atleast how to go abt it ???

just d start of it ???
Paul D from Canada  [45 posts] 15 year
First you need to isolate the overall cube and then the squares - try the blob filter by shape and color.
If not, try shape matching.

With the cube isolated, use geometry stats to give you the coordinates of the cube.
Determine the centers of the 9 areas based on mid-points.
Use sample color module to match expected colors or the sampled colors from the other image.

If you post problems with a RoboRealm module you have been working with, people may be more willing to help.

Try looking at the tutorials for some guidance.
Anonymous 15 year
thank u so much .. it really gave me a brisk start ..

here is my doubt no 1:::

for ex ... i ve isolate only d green components from the picture ... i dont know exaclty the shade of green ... but the shade of green is gng to be the same in all the sequence of pictures i am gng to take ...

now can i take a sample picture and store the exact shade of green so dat i can compare dem wid d further sequence of images i am gng to take ???

thank u for u kind support ...
Anonymous 15 year
Try the below robofile.

1. Segments image into distinct blobs
2. Negative - makes dark blobs white
3. Blob Filter - filters for the largest white blob (originally black ones)
4. Blob Replace - replaces the largest blob with a square around the blob
5. Erode 10 - remove a little around the outside of the square since we are not using an affine transform
6. Math - used to mask just the cube from the image ... now we can focus on just the cube
7. Affine - transform the cube face into a nice square
8. Mean - smooth the colors a little
9. Pixelate - replace each color block with its most frequent color
10. Blob_Colorize - then replace each color against a reference color.

Now you have an ideal model of the cube. It should be easy to either use the API to grab the image or even the VBScript to get direct access to the pixels. The pixel colors will be exactly those specified in the blob_colorize so you will know what color it is by checking the specific value.

Make sense? You've got a little more to go but we'll let you take it from here to finish your class project.


Anonymous 15 year
Actually, if you try the robofile below you can then look at the BLOB_COLORIZE_LABELS variable which will list in a bottom up order the colors and the COG of each color. The list of colors should be in the same order for both images. You can use that list and a little code to compare the two. Note that the 'color' strings that is uses comes from the Blob_Colorize module.

Anonymous 15 year
thanks a lot ..

i ll work on dese now .. and ask u if at all i get some doubts in d future ..

dat was a gr8 explanation ... which almost got rid of all my doubts ...

thanks a lot once again ...

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