Develop Reference

Thresholding in Android using opencv

Not sure if this is the right way to ask, but please help. I have an image of a dented car. I have to process it and highlight the dents and return the number of dents. I was able to do it reasonably well with the following result:
The matlab code is:
img2=rgb2gray(i1);
imshow(img2);
img3=imtophat(img2,strel('disk',15));
img4=imadjust(img3);
layer=img4(:,:,1);
img5=layer>100 & layer<250;
img6=imfill(img5,'holes');
img7=bwareaopen(img6,5);
[L,ans]=bwlabeln(img7);
imshow(img7);
I=imread(i1);
Ians=CarDentIdentification(I);
However, when I try to do this using opencv, I get this:
With the following code:
Imgproc.cvtColor(source, middle, Imgproc.COLOR_RGB2GRAY);
Imgproc.equalizeHist(middle, middle);
Imgproc.threshold(middle, middle, 150, 255, Imgproc.THRESH_OTSU);
Please tell me how can I obtain better results in opencv, and also how to count the dents? I tried findcontour() but it gives a very large number. I tried on other images as well, but I'm not getting proper results.
Please help.

So you basically from the MATLAB site, imtophat does - Top-hat filtering computes the morphological opening of the image (using imopen) and then subtracts the result from the original image.
You could do this in OpenCV with the following steps:
Step 1: Get the disk structuring element
kernel = cv2.getStructuringElement(cv2.MORPH_ELLIPSE, (15, 15))
Step 2: Compute opening of the image and then subtract the result from the original image
tophat = cv2.morphologyEx(v, cv2.MORPH_TOPHAT, kernel)
This gives following result -
Step 3 - Now you could just manually threshold it or use Otsu -
ret, thresh = cv2.threshold(tophat, 17, 255, 0)
which gives you the following image -
Since the OP wants the code in Java, here is the probable code in Java:
private Mat topHat(Mat image)
{
Mat element = Imgproc.getStructuringElement(Imgproc.MORPH_ELLIPSE, new Size(15, 15), new Point (0, 0));
Mat dst = new Mat;
Imgproc.morphologyEx(image, dst, Imgproc.MORPH_TOPHAT, element, new Point(0, 0));
return dst;
}
Make sure you do this on a gray scale image (CvType.8UC1) and then you can threshold suitably.

Issue with using filters with libgdx, mipmapping specifically

I am currently running into issues right now when I render my background image for my app. It has jagged edges in it as you can see:
http://imgur.com/a/doqvI
Now, here is the code which I am using to load the image in, and I have tried all possible combinations of the filtering so this is not the only one I have tried.
newPenguinGraphic = new Texture(Gdx.files.internal("data/1024Set1.png"),true);
texture.setFilter(TextureFilter.MipMapLinearNearest, TextureFilter.Nearest);
Screen setup:
float gameWidth = 330;
float gameHeight = screenHeight / (screenWidth / gameWidth);
int midPointY = (int) (gameHeight / 2);
Cam:
cam = new OrthographicCamera();
cam.setToOrtho(true, 330, gameHeight);
Graphic:
MainBackground = new BGScroller(0, yPos-165, 330, 220, SCROLL_SPEED, yPos);
The size of the original image is 688x459 also btw.
A question I have been wondering, do I need to generate the mipmap png files before and load them in manually or does libgdx literally create them at runtime? Please help, and thanks!!

compare 2 images to avoid duplication

I am comparing 2 similar images and would like to see if both are similar .Currently I used the code:
public void foo(Bitmap bitmapFoo) {
int[] pixels;
int height = bitmapFoo.getHeight();
int width = bitmapFoo.getWidth();
pixels = new int[height * width];
bitmapFoo.getPixels(pixels, 0, width, 1, 1, width - 1, height - 1);
}
and I call the function : foo(img1) where :
img1=(Bitmap)data.getExtras().get("data");
I would like to know how to get the above getpixel,I tried assigning it to variable but did not work .Should it have a return type ?? and in format it is ?
And also how do I compare 2 images??
Also both the images may be of different dimensions based on the mobile camera the snapshot is taken from .
Also can it recognize if the same image is shot in the morning and night ???
Thanks in Advance.

This code will compare pixel from base image with other image.
If both pixel at location (x,y) are same then add same pixel in result image without change. Otherwise it modifies that pixel and add to our result image.
In case of baseline image height or width is larger than other image then it will add red color for extra pixel which is not available in other images.
Both image file format should be same for comparison.
Code will use base image file format to create resultant image file and resultant image contains highlighted portion where difference observed.
Here is a Link To Code with sample example attached.

If you want to copy the pixels of the bitmap to a byte array, the easiest way is:
int height = bitmapFoo.getHeight();
int width = bitmapFoo.getWidth();
pixels = new int[height * width];
bitmapFoo.copyPixelsToBuffer(pixels);
See the documentation
I should warn you that you will have to handle this with care, any other way you will get OutOfMemoryError.
To get All Pixels
bitmapFoo.copyPixelsToBuffer(pixels);
or
bitmapFoo.getPixels(pixels, 0, width, 0, 0, width, height);
To get One Pixel
The two arguments must be two integers within the range [0, getWidth()-1] and [0, getHeight()-1]
int pix = bitmapFoo.getPixel(x, y);

how to merge Images and impose on each other

Suppose I'm uploading two or more than two pics in some Framelayout. Hereby I'm uploading three pics with a same person in three different position in all those three pictures. Then what image processing libraries in Android or java or Native's are available to do something as shown in the pic.
I would like to impose multiple pictures on each other.
Something like these:-
One idea is to :
Do some layering in all those pictures and find mismatching areas in the pics and merge them.
How one can merge multiple picture with other? By checking the di-similarity and merge with each other?
Are there any Third party Api's or some Photoshop service which can help me in doing these kinda image processing?

In this case you are not just trying to combine the images. You really want to combine a scene containing the same object in different positions.
Therefore, it is not just a simple combination or an alpha compositve where the color of a given pixel in the output image is the sum of the value of this pixel in each image, divided by the number of images.
In this case, you might do:
Determine the scene background analysing the pixels that do not change considering multiple images.
Begin with the output image being just the background.
For each image, remove the background to get the desired object and combine it with the output image.
There is a Marvin plug-in to perform this task, called MergePhoto. The program below use that plug-in to combine a set of parkour photos.
import marvin.image.MarvinImage;
import marvin.io.MarvinImageIO;
import marvin.plugin.MarvinImagePlugin;
import marvin.util.MarvinPluginLoader;
public class MergePhotosApp {
public MergePhotosApp(){
// 1. load images 01.jpg, 02.jpg, ..., 05.jpg into a List
List<MarvinImage> images = new ArrayList<MarvinImage>();
for(int i=1; i<=5; i++){
images.add(MarvinImageIO.loadImage("./res/0"+i+".jpg"));
}
// 2. Load plug-in and process the image
MarvinImagePlugin merge = MarvinPluginLoader.loadImagePlugin("org.marvinproject.image.combine.mergePhotos");
merge.setAttribute("threshold", 38);
// 3. Process the image list and save the output
MarvinImage output = images.get(0).clone();
merge.process(images, output);
MarvinImageIO.saveImage(output, "./res/merge_output.jpg");
}
public static void main(String[] args) {
new MergePhotosApp();
}
}
The input images and the output image are shown below.

I don't know if this will qualify to be in your definition of "natives", but there is the following .NET library that could help: http://dynamicimage.apphb.com/
If the library itself can give you want you want, then depending on your architecture you could set up a small ASP.NET site to do the image manipulation on the server.

Check the accepted answer here.
In above link there is merging of two images which is done by openCV sdk.
If you dont want to use openCV and just want to try with your self then you will have to play little with framlayout and with three imageview. Give options to user to select specific part of the image to show for all three images. So the selected part will be shown of the selected image. on this way you will get the result like above what you have said.
Hope you got my point. If not then let me know.
Enjoy coding... :)

You can overlay the images using openCV you can check at OpenCV and here or here
// Read the main background image
cv::Mat image= cv::imread("Background.png");
// Read the mans character image to be placed
cv::Mat character= cv::imread("character.png");
// define where you want to place the image
cv::Mat newImage;
//The 10,10 are the initial coordinates in pixels
newImage= image(cv::Rect(10,10,character.cols,character.rows));
// add it to the background, The 1 is the aplha values
cv::addWeighted(newImage,1,character,1,0,newImage);
// show result
cv::namedWindow("with character");
cv::imshow("with character",image);
//Write Image
cv::imwrite("output.png", newImage);
or you can create it as a watermark effect
Or you can try it in java like merging two images
try using this class
public class MergeImages {
public static void main(String[] args) {
File inner = new File("Inner.png");
File outter = new File("Outter.png");
try {
BufferedImage biInner = ImageIO.read(inner);
BufferedImage biOutter = ImageIO.read(outter);
System.out.println(biInner);
System.out.println(biOutter);
Graphics2D g = biOutter.createGraphics();
g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.8f));
int x = (biOutter.getWidth() - biInner.getWidth()) / 2;
int y = (biOutter.getHeight() - biInner.getHeight()) / 2;
System.out.println(x + "x" + y);
g.drawImage(biInner, x, y, null);
g.dispose();
ImageIO.write(biOutter, "PNG", new File("Outter.png"));
} catch (Exception e) {
e.printStackTrace();
}
}
}

Template Matching for android-opencv application

I have developed an algorithm for android using OpenCV. I need to find overlap between the previous image and current frame. So, I have produced the template from previous image to match with current frame to make a photograph. It is the procedure to complete photographing. (Taking more than 10 picture)
Here is the code that I have developed to find the overlap.
public void overlapFinder(Mat inputFrame , Mat inputTemplate )
{
Mat mResult;
int resultWidth = inputFrame.width() - inputTemplate.width() + 1;
int resultHeight = inputFrame.height() - inputTemplate.height() + 1;
mResult = new Mat(resultHeight, resultWidth, CvType.CV_8U);
Imgproc.matchTemplate(inputFrame, inputTemplate, mResult,Imgproc.TM_CCORR_NORMED) ;
Core.MinMaxLocResult result = Core.minMaxLoc(mResult);
#SuppressWarnings("unused")
double maxVal = result.maxVal;
}
The problem is that when the "overlap function" is called after generating template from previous image, the application is crashed.
Would anyone please help me with that?
Thanks

Maybe you really need to do some debugging first, but in any case, I can see from your code that it would be worthwhile checking the sizes of your images - it seems that your code assumes the template is always smaller than the input frame.
If that's not true, you will get negative resultWidth and/or resultHeight, which will make it crash.
One other thing - the documentation suggests that the result type should be CV_32FC1.
PS - Try initialising your result like this:
mResult.create(resultHeight, resultWidth, CvType.CV_32FC1);