CODEWITHSUNDEEP
pythonopencvtypeerrorsrc
autonocat
autonocat

Reputation: 767

OpenCV TypeError: Expected cv::UMat for argument 'src' - What is this?

Disclaimer: huge openCV noob

Traceback (most recent call last):

File "lanes2.py", line 22, in 

canny = canny(lane_image)

File "lanes2.py", line 5, in canny

gray = cv2.cvtColor(imgUMat, cv2.COLOR_RGB2GRAY)

TypeError: Expected cv::UMat for argument 'src'

What exactly is 'src' referring to?

Upvotes: 73

Views: 395815

Answers (15)

mustafa candan
mustafa candan

Reputation: 846

If you are using byte object instead of reading from file you can convert your image to numpy array like this

image = numpy.array(Image.open(io.BytesIO(image_bytes)))

Upvotes: 0

Navid Naderi
Navid Naderi

Reputation: 350

Convert your image matrix to ascontiguousarray using np.ascontiguousarray as bellow:

gray = cv2.cvtColor(np.ascontiguousarray(imgUMat), cv2.COLOR_RGB2GRAY)

Upvotes: 5

Geo
Geo

Reputation: 11

I got round thid by writing/reading to a file. I guessed cv.imread would put it into the format it needed. This code for anki Vector SDK program but you get the idea.

tmpImage = robot.camera.latest_image.raw_image.save('temp.png')         
pilImage = cv.imread('temp.png')

Upvotes: 0

Amar Sagat
Amar Sagat

Reputation: 43

Just add this at start:

image = cv2.imread(image)

Upvotes: 4

Marcus Palmer
Marcus Palmer

Reputation: 11

Verify the application root folder is the same as the file you are attempting to run.

Upvotes: 0

TehDrunkSailor
TehDrunkSailor

Reputation: 780

If using ImageGrab

Verify that your image is not a 0x0 area due to an incorrect bbox.

Upvotes: 0

Varun Mathur
Varun Mathur

Reputation: 918

src is the first argument to cv2.cvtColor.

The error you are getting is because it is not the right form. cv2.Umat() is functionally equivalent to np.float32(), so your last line of code should read:

gray = cv2.cvtColor(np.float32(imgUMat), cv2.COLOR_RGB2GRAY)

Upvotes: 61

code-freeze
code-freeze

Reputation: 485

that is referring to the expected dtype of your image
"image".astype('float32') should solve your issue

Upvotes: 1

Oliver Zendel
Oliver Zendel

Reputation: 2901

Some dtype are not supported by specific OpenCV functions. For example inputs of dtype np.uint32 create this error. Try to convert the input to a supported dtype (e.g. np.int32 or np.float32)

Upvotes: 2

Avi Avidan
Avi Avidan

Reputation: 1096

The following can be used from numpy:

import numpy as np 
image = np.array(image)

Upvotes: 23

Dmitriy Kisil
Dmitriy Kisil

Reputation: 2998

Sometimes I have this error when videostream from imutils package doesn't recognize frame or give an empty frame. In that case, solution will be figuring out why you have such a bad frame or use a standard VideoCapture(0) method from opencv2

Upvotes: 0

Hazarapet Tunanyan
Hazarapet Tunanyan

Reputation: 2865

This is a general error, which throws sometimes, when you have mismatch between the types of the data you use. E.g I tried to resize the image with opencv, it gave the same error. Here is a discussion about it.

Upvotes: 2

Maximilian
Maximilian

Reputation: 774

Not your code is the problem this is perfectly fine:

gray = cv2.cvtColor(imgUMat, cv2.COLOR_RGB2GRAY)

The problem is that imgUMat is None so you probably made a mistake when loading your image: 

imgUMat = cv2.imread("your_image.jpg")

I suspect you just entered the wrong image path.

Upvotes: 11

Nuzhny
Nuzhny

Reputation: 1927

gray = cv2.cvtColor(cv2.UMat(imgUMat), cv2.COLOR_RGB2GRAY)

UMat is a part of the Transparent API (TAPI) than help to write one code for the CPU and OpenCL implementations.

Upvotes: 28

Daweo
Daweo

Reputation: 36570

Is canny your own function? Do you use Canny from OpenCV inside it? If yes check if you feed suitable argument for Canny - first Canny argument should meet following criteria:

  • type: <type 'numpy.ndarray'>
  • dtype: dtype('uint8')
  • being single channel or simplyfing: grayscale, that is 2D array, i.e. its shape should be 2-tuple of ints (tuple containing exactly 2 integers)

You can check it by printing respectively

type(variable_name)
variable_name.dtype
variable_name.shape

Replace variable_name with name of variable you feed as first argument to Canny.

Upvotes: 2

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