bytedeco/javacv

OpenCVDemo in DeepLearningFaceDetection：error: (-215:Assertion failed) nch == 1 in function 'blobFromImages'

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#1,458 opened on Jun 26, 2020

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Description

 Caused by: java.lang.RuntimeException: OpenCV(4.3.0) /home/travis/build/javacpp-presets/opencv/cppbuild/android-arm64/opencv-4.3.0/modules/dnn/src/dnn.cpp:398: error: (-215:Assertion failed) nch == 1 in function 'blobFromImages'
    
        at org.bytedeco.opencv.global.opencv_dnn.blobFromImage(Native Method)

The error is on line 51

Mat blob = blobFromImage(image, 1.0, new Size(300, 300), new Scalar(104.0, 177.0, 123.0, 0), false, false, CV_32F);

Contributor guide

Research direction
Investigate the assertion failure 'nch == 1' in OpenCV's blobFromImages function. The error occurs in the Android build. Check if the input image has more than one channel or if the blobFromImage call with CV 32F is correct. Ensure the image is loaded correctly (e.g., as grayscale or BGR).
Tech stack
java
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
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Fresh
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Clear
Prerequisites
JavaGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70