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Fix minor errors in the first documentation page (Introduction)

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This markdown file corresponds to the first link on the landing
page of OpenCV documentation.
This commit is contained in:
lamm45 2022-06-24 13:49:40 -04:00
parent 6234f01a6d
commit 9faefa0c96
1 changed files with 12 additions and 12 deletions
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modules/core/doc/intro.markdown
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@ -71,7 +71,7 @@ data sharing. A destructor decrements the reference counter associated with the
The buffer is deallocated if and only if the reference counter reaches zero, that is, when no other The buffer is deallocated if and only if the reference counter reaches zero, that is, when no other
structures refer to the same buffer. Similarly, when a Mat instance is copied, no actual data is structures refer to the same buffer. Similarly, when a Mat instance is copied, no actual data is
really copied. Instead, the reference counter is incremented to memorize that there is another owner really copied. Instead, the reference counter is incremented to memorize that there is another owner
of the same data. There is also the Mat::clone method that creates a full copy of the matrix data. of the same data. There is also the cv::Mat::clone method that creates a full copy of the matrix data.
See the example below: See the example below:
```.cpp ```.cpp
// create a big 8Mb matrix // create a big 8Mb matrix
@ -159,11 +159,11 @@ grayscale conversion. Note that frame and edges are allocated only once during t
of the loop body since all the next video frames have the same resolution. If you somehow change the of the loop body since all the next video frames have the same resolution. If you somehow change the
video resolution, the arrays are automatically reallocated. video resolution, the arrays are automatically reallocated.
The key component of this technology is the Mat::create method. It takes the desired array size and The key component of this technology is the cv::Mat::create method. It takes the desired array size
type. If the array already has the specified size and type, the method does nothing. Otherwise, it and type. If the array already has the specified size and type, the method does nothing. Otherwise,
releases the previously allocated data, if any (this part involves decrementing the reference it releases the previously allocated data, if any (this part involves decrementing the reference
counter and comparing it with zero), and then allocates a new buffer of the required size. Most counter and comparing it with zero), and then allocates a new buffer of the required size. Most
functions call the Mat::create method for each output array, and so the automatic output data functions call the cv::Mat::create method for each output array, and so the automatic output data
allocation is implemented. allocation is implemented.
Some notable exceptions from this scheme are cv::mixChannels, cv::RNG::fill, and a few other Some notable exceptions from this scheme are cv::mixChannels, cv::RNG::fill, and a few other
@ -247,9 +247,9 @@ Examples:
// matrix (10-element complex vector) // matrix (10-element complex vector)
Mat img(Size(1920, 1080), CV_8UC3); // make a 3-channel (color) image Mat img(Size(1920, 1080), CV_8UC3); // make a 3-channel (color) image
// of 1920 columns and 1080 rows. // of 1920 columns and 1080 rows.
Mat grayscale(image.size(), CV_MAKETYPE(image.depth(), 1)); // make a 1-channel image of Mat grayscale(img.size(), CV_MAKETYPE(img.depth(), 1)); // make a 1-channel image of
// the same size and same // the same size and same
// channel type as img // channel type as img
``` ```
Arrays with more complex elements cannot be constructed or processed using OpenCV. Furthermore, each Arrays with more complex elements cannot be constructed or processed using OpenCV. Furthermore, each
function or method can handle only a subset of all possible array types. Usually, the more complex function or method can handle only a subset of all possible array types. Usually, the more complex
@ -269,14 +269,14 @@ extended in future based on user requests.
### InputArray and OutputArray ### InputArray and OutputArray
Many OpenCV functions process dense 2-dimensional or multi-dimensional numerical arrays. Usually, Many OpenCV functions process dense 2-dimensional or multi-dimensional numerical arrays. Usually,
such functions take cppMat as parameters, but in some cases it's more convenient to use such functions take `cv::Mat` as parameters, but in some cases it's more convenient to use
`std::vector<>` (for a point set, for example) or `cv::Matx<>` (for 3x3 homography matrix and such). To `std::vector<>` (for a point set, for example) or `cv::Matx<>` (for 3x3 homography matrix and such). To
avoid many duplicates in the API, special "proxy" classes have been introduced. The base "proxy" avoid many duplicates in the API, special "proxy" classes have been introduced. The base "proxy"
class is cv::InputArray. It is used for passing read-only arrays on a function input. The derived from class is cv::InputArray. It is used for passing read-only arrays on a function input. The derived from
InputArray class cv::OutputArray is used to specify an output array for a function. Normally, you should InputArray class cv::OutputArray is used to specify an output array for a function. Normally, you should
not care of those intermediate types (and you should not declare variables of those types not care of those intermediate types (and you should not declare variables of those types
explicitly) - it will all just work automatically. You can assume that instead of explicitly) - it will all just work automatically. You can assume that instead of
InputArray/OutputArray you can always use `Mat`, `std::vector<>`, `cv::Matx<>`, `cv::Vec<>` or `cv::Scalar`. When a InputArray/OutputArray you can always use `cv::Mat`, `std::vector<>`, `cv::Matx<>`, `cv::Vec<>` or `cv::Scalar`. When a
function has an optional input or output array, and you do not have or do not want one, pass function has an optional input or output array, and you do not have or do not want one, pass
cv::noArray(). cv::noArray().
@ -288,7 +288,7 @@ the optimization algorithm did not converge), it returns a special error code (t
boolean variable). boolean variable).
The exceptions can be instances of the cv::Exception class or its derivatives. In its turn, The exceptions can be instances of the cv::Exception class or its derivatives. In its turn,
cv::Exception is a derivative of std::exception. So it can be gracefully handled in the code using cv::Exception is a derivative of `std::exception`. So it can be gracefully handled in the code using
other standard C++ library components. other standard C++ library components.
The exception is typically thrown either using the `#CV_Error(errcode, description)` macro, or its The exception is typically thrown either using the `#CV_Error(errcode, description)` macro, or its
@ -297,7 +297,7 @@ printf-like `#CV_Error_(errcode, (printf-spec, printf-args))` variant, or using
satisfied. For performance-critical code, there is #CV_DbgAssert(condition) that is only retained in satisfied. For performance-critical code, there is #CV_DbgAssert(condition) that is only retained in
the Debug configuration. Due to the automatic memory management, all the intermediate buffers are the Debug configuration. Due to the automatic memory management, all the intermediate buffers are
automatically deallocated in case of a sudden error. You only need to add a try statement to catch automatically deallocated in case of a sudden error. You only need to add a try statement to catch
exceptions, if needed: : exceptions, if needed:
```.cpp ```.cpp
try try
{ {