OpenCV  4.10.0-dev
Open Source Computer Vision
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cv::ImageCollection Class Reference

To read multi-page images on demand. More...

#include <opencv2/imgcodecs.hpp>

Collaboration diagram for cv::ImageCollection:


struct  iterator

Public Member Functions

 ImageCollection ()
 ImageCollection (const String &filename, int flags)
const Matat (int index)
iterator begin ()
iterator end ()
Ptr< Impl > getImpl ()
void init (const String &img, int flags)
const Matoperator[] (int index)
void releaseCache (int index)
size_t size () const

Protected Attributes

Ptr< Impl > pImpl

Detailed Description

To read multi-page images on demand.

The ImageCollection class provides iterator API to read multi-page images on demand. Create iterator to the collection of the images and iterate over the collection. Decode the necessary page with operator*.

The performance of page decoding is O(1) if collection is increment sequentially. If the user wants to access random page, then the time Complexity is O(n) because the collection has to be reinitialized every time in order to go to the correct page. However, the intermediate pages are not decoded during the process, so typically it's quite fast. This is required because multi-page codecs does not support going backwards. After decoding the one page, it is stored inside the collection cache. Hence, trying to get Mat object from already decoded page is O(1). If you need memory, you can use .releaseCache() method to release cached index. The space complexity is O(n) if all pages are decoded into memory. The user is able to decode and release images on demand.

Constructor & Destructor Documentation

◆ ImageCollection() [1/2]

cv::ImageCollection::ImageCollection ( )

◆ ImageCollection() [2/2]

cv::ImageCollection::ImageCollection ( const String filename,
int  flags 

Member Function Documentation

◆ at()

const Mat & cv::ImageCollection::at ( int  index)

◆ begin()

iterator cv::ImageCollection::begin ( )

◆ end()

iterator cv::ImageCollection::end ( )

◆ getImpl()

Ptr< Impl > cv::ImageCollection::getImpl ( )

◆ init()

void cv::ImageCollection::init ( const String img,
int  flags 

◆ operator[]()

const Mat & cv::ImageCollection::operator[] ( int  index)

◆ releaseCache()

void cv::ImageCollection::releaseCache ( int  index)

◆ size()

size_t cv::ImageCollection::size ( ) const

Member Data Documentation

◆ pImpl

Ptr<Impl> cv::ImageCollection::pImpl

The documentation for this class was generated from the following file: