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);
Related
I am kind of stuck with this problem, and I know there are so many questions about it on stack overflow but in my case. Nothing gives the expected result.
The Context:
Am using Android OpenCV along with Tesseract so I can read the MRZ area in the passport. When the camera is started I pass the input frame to an AsyncTask, the frame is processed, the MRZ area is extracted succesfully, I pass the extracted MRZ area to a function prepareForOCR(inputImage) that takes the MRZ area as gray Mat and Will output a bitmap with the thresholded image that I will pass to Tesseract.
The problem:
The problem is while thresholding the Image, I use adaptive thresholding with blockSize = 13 and C = 15, but the result given is not always the same depending on the lighting of the image and the conditions in general from which the frame is taken.
What I have tried:
First I am resizing the image to a specific size (871,108) so the input image is always the same and not dependant on which phone is used.
After resizing, I try with different BlockSize and C values
//toOcr contains the extracted MRZ area
Bitmap toOCRBitmap = Bitmap.createBitmap(bitmap);
Mat inputFrame = new Mat();
Mat toOcr = new Mat();
Utils.bitmapToMat(toOCRBitmap, inputFrame);
Imgproc.cvtColor(inputFrame, inputFrame, Imgproc.COLOR_BGR2GRAY);
TesseractResult lastResult = null;
for (int B = 11; B < 70; B++) {
for (int C = 11; C < 70; C++){
if (IsPrime(B) && IsPrime(C)){
Imgproc.adaptiveThreshold(inputFrame, toOcr, 255, Imgproc.ADAPTIVE_THRESH_GAUSSIAN_C, Imgproc.THRESH_BINARY, B ,C);
Bitmap toOcrBitmap = OpenCVHelper.getBitmap(toOcr);
TesseractResult result = TesseractInstance.extractFrame(toOcrBitmap, "ocrba");
if (result.getMeanConfidence()> 70) {
if (MrzParser.tryParse(result.getText())){
Log.d("Main2Activity", "Best result with " + B + " : " + C);
return result;
}
}
}
}
}
Using the code below, the thresholded result image is a black on white image which gives a confidence greater than 70, I can't really post the whole image for privacy reasons, but here's a clipped one and a dummy password one.
Using the MrzParser.tryParse function which adds checks for the character position and its validity within the MRZ, am able to correct some occurences like a name containing a 8 instead of B, and get a good result but it takes so much time, which is normal because am thresholding almost 255 images in the loop, adding to that the Tesseract call.
I already tried getting a list of C and B values which occurs the most but the results are different.
The question:
Is there a way to define a C and blocksize value so that it s always giving the same result, maybe adding more OpenCV calls so The input image like increasing contrast and so on, I searched the web for 2 weeks now I can't find a viable solution, this is the only one that is giving accurate results
You can use a clustering algorithm to cluster the pixels based on color. The characters are dark and there is a good contrast in the MRZ region, so a clustering method will most probably give you a good segmentation if you apply it to the MRZ region.
Here I demonstrate it with MRZ regions obtained from sample images that can be found on the internet.
I use color images, apply some smoothing, convert to Lab color space, then cluster the a, b channel data using kmeans (k=2). The code is in python but you can easily adapt it to java. Due to the randomized nature of the kmeans algorithm, the segmented characters will have label 0 or 1. You can easily sort it out by inspecting cluster centers. The cluster-center corresponding to characters should have a dark value in the color space you are using.
I just used the Lab color space here. You can use RGB, HSV or even GRAY and see which one is better for you.
After segmenting like this, I think you can even find good values for B and C of your adaptive-threshold using the properties of the stroke width of the characters (if you think the adaptive-threshold gives a better quality output).
import cv2
import numpy as np
im = cv2.imread('mrz1.png')
# convert to Lab
lab = cv2.cvtColor(cv2.GaussianBlur(im, (3, 3), 1), cv2.COLOR_BGR2Lab)
im32f = np.array(im[:, :, 1:3], dtype=np.float32)
k = 2 # 2 clusters
term_crit = (cv2.TERM_CRITERIA_EPS, 30, 0.1)
ret, labels, centers = cv2.kmeans(im32f.reshape([im.shape[0]*im.shape[1], -1]),
k, None, term_crit, 10, 0)
# segmented image
labels = labels.reshape([im.shape[0], im.shape[1]]) * 255
Some results:
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.
I'm trying to make my app detect when two bitmaps intersect each other. This is the code I tried for collision:
//width and height of the two bitmaps
int width1 = bplay1.getWidth();
int height1 = bplay1.getHeight();
int width2 = bbrick1.getWidth();
int height2 = bbrick1.getHeight();
if (height1 < height2)
if ( width1 < width2)
{
currentscore.setText("collision detected");
}
However, the app crashes on start when I use getHeight() and getWidth(). Am I doing something wrong with it?
If it crashes, what output does it generate in the crash (in logcat)?
Assuming it crashes with null pointer exception (which to me seems most likely based on the very terse information you provided), you should make sure your bplay1 and/or bbrick1 objects are not null like so: bplay1 = new MyClass();
Summary: Whenever you post a S.O. question ask yourself this: If I found this post, what information would I be likely to need to solve it? In this specific case there is actually very little to go on.
I used this code to copy a piece of texture to another texture , it did work on Windows , but on Android it didn't . How can i fix it ?
Here my code :
public int DerivationGraph(int SrcX, int SrcY, int Width, int Height, int SrcGraphHandle)
{
Texture2D originalTexture = _textureCache[SrcGraphHandle];
Rectangle sourceRectangle = new Rectangle(SrcX, SrcY, Width, Height);
Texture2D cropTexture = new Texture2D(GraphicsDevice, sourceRectangle.Width, sourceRectangle.Height);
Color[] data = new Color[sourceRectangle.Width * sourceRectangle.Height];
originalTexture.GetData(0, sourceRectangle, data, 0, data.Length);
cropTexture.SetData(data);
int nextIndex = textureIndex + 1;
_textureCache[nextIndex] = cropTexture;
textureIndex++;
return textureIndex;
}
I was looking into the same thing, and unfortunately it appears that the particular overload that uses a source rectangle simply does not work. From what I have found, the problem comes from OpenGL ES-2.0 not supporting reads after video memory has been loaded.
From this discussion on the MonoGame Develop branch:
tomspilman commented on Feb 19, 2013
you could not read back texture data once it was uploaded to video memory
That particular discussion is about the iOS implementation of GetData(), but it makes mention of the Android overloads and there being a workaround involved in getting it to work.
Personally, I have tried the generic method for GetData() on Android and it does in fact work. The source rectangle method, however, does not return any data using OpenGL ES 1.1 or 2.0.
Getting the entire texture data may be your only solution.
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();
}
}
}