Android Question Fill color boxes automatically.

[vecino]

Hello, is it possible or not possible?

The user uploads an image.
The software "finds" the boxes and filled with color.
The software saves the new image.

Impossible?

User image:

Generated image:

 

[DonManfred]

Impossible?

No

 

[RandomCoder]

Very helpful @DonManfred (and completely off-topic but I like the new Avatar ).

So it's got me thinking, how would someone go about doing this?
I'm thinking that maybe create a Type called box...

Type Box(Num As Int, x1 As Int, y1 As Int, x2 As Int, y2 As Int, Colour As Int)

Then create a canvas containing the image and scan from to left to right getting each individual pixel. Black pixels denote the edge of a box. Move down to the next row of pixels and repeat also checking for the bottom edge of the boxes.
Or, would it be easier to find the first box edge and bottom then move to finding the next box edge and bottom

 

[DonManfred]

and completely off-topic

It is NOT off-topic! He asked "Impossible?" and i gave the answer that it is not impossible.

SO WHAT?

 

[RandomCoder]

Oh you do seem techy today @DonManfred
You have misunderstood me, I was referring to myself being off topic with regard to your Avatar! That was all I meant by it

 

[sorex]

it's possible but it might be slow on cheaper slower devices.

 

[DonManfred]

You have misunderstood me, I was referring to myself being off topic with regard to your Avatar! That was all I meant by it

Sorry then

I like the new avatar too

 

[vecino]

Then, do you have any idea?

 

[Troberg]

Here's how I'd do it:

1. Find a white pixel.
2. Do a floodfill from that pixel in another color.
3. Repeat until there are no white pixels left.

 

[stevel05]

This is tricky, it will depend on the quality of the image. Flood fill would be good (is there a library that implements this?) if boundaries are all solid, and the background is white, not grey, or off white. I did a quick scan of the internet and there are a few links to java code that may do it. Try searching for one that looks promising and see if it can be ported. I'm sure there is a 'proper' way to do it and you may just stumble across a quick or at least accurate method.

 

[vecino]

.. if boundaries are all solid, and the background is white, not grey, or off white.

Yes, black and white

 

[sorex]

the problem here is that you need to start over again after every fill since you don't know where the fills have drawn already.

so the more polygons you have the slower it will become.

this is not the case if the fill only occurs on an offset based on a press/touch on the picture.

 

[vecino]

Yes, I understand

 

[sorex]

can they only upload poly pictures like the one in the example or are they free?

if it is only squares you can make it really fast.

 

[vecino]

The polygons may be squares, rectangles, triangles, etc.

 

[sorex]

ok, then you can't benefit the fast scanning and plotting methods I had in mind.

 

[vecino]

Wow, bad luck

 

[Troberg]

How many polygons can you expect? If it's few, my floodfil method will be plenty fast, but if it's thousands, you might want to reconsider.

 

[sorex]

if you know in advance where they are it can be fast but you need to rescan the image after every fill again to find and do the next none filled area.

you can store the last position then you can skip some of it.

 

[Troberg]

You can also do the scanning smarter. Remember how far you scanned last time before finding a white pixel, and resume from that point the next time. It's not like non-white pixels are going to turn white, so no need to re-scan.

Smart scanning like this, combined with flood fill, is probably as close to optimal as you can get with a reasonably simple algoritm.