====== OpenCV ======

===== Instalação =====

==== Pré-Requisitos ====

<code>pip install numpy</code>

<code>pip install matplotlib</code>

<code>pip install opencv-python</code>

=== Importar uma imagem ===

<file python image.py>
import cv2 as cv
import sys

#chama a funcao cv::imread e cria e armazena um objeto cv:Mat
img = cv.imread(cv.samples.findFile("starry_night.jpg"))

#verifica se a imagem foi carregada corretamente
if img is None:
   sys.exit("Could not read the image.")
  
#cria uma janela para mostrar a imagem - arg1 = nome da janela, arg2 = obj cv:Mat
cv.imshow("Display window", img)

#funcao cv:waitkey tempo de espera, entrada em milisegundos, '0' significa para sempre
k = cv.waitKey(0)

#pressiona 's' para salvar o arquivo
if k == ord("s"):
#funcao cv:imwrite salva o objeto cv:Mat como png
   cv.imwrite("starry_night.png", img)
</file>

Utilize a imagem abaixo para o teste:
\\
{{:starry_night.jpg?50|}}


==== imread() ====

Python:
cv.imread(	filename[, flags]	) ->	retva

=== filename ===

Formatos suportados:
  * Windows bitmaps - *.bmp, *.dib (always supported)
  * JPEG files - *.jpeg, *.jpg, *.jpe (see the Note section)
  * JPEG 2000 files - *.jp2 (see the Note section)
  * Portable Network Graphics - *.png (see the Note section)
  * WebP - *.webp (see the Note section)
  * AVIF - *.avif (see the Note section)
  * Portable image format - *.pbm, *.pgm, *.ppm *.pxm, *.pnm (always supported)
  * PFM files - *.pfm (see the Note section)
  * Sun rasters - *.sr, *.ras (always supported)
  * TIFF files - *.tiff, *.tif (see the Note section)
  * OpenEXR Image files - *.exr (see the Note section)
  * Radiance HDR - *.hdr, *.pic (always supported)
  * Raster and Vector geospatial data supported by GDAL (see the Note section)

=== flags (não obrigatório) ===
  * cv.IMREAD_UNCHANGED
  * cv.IMREAD_GRAYSCALE
  * **cv.IMREAD_COLOR - PADRÂO**
  * cv.IMREAD_ANYDEPTH
  * cv.IMREAD_ANYCOLOR
  * cv.IMREAD_LOAD_GDAL
  * cv.IMREAD_REDUCED_GRAYSCALE_2
  * cv.IMREAD_REDUCED_COLOR_2
  * cv.IMREAD_REDUCED_GRAYSCALE_4
  * cv.IMREAD_IGNORE_ORIENTATION 

Referências:

[[https://docs.opencv.org/4.x/d5/de5/tutorial_py_setup_in_windows.html|Install OpenCV-Python Windows]]

[[https://docs.opencv.org/4.x/d6/d00/tutorial_py_root.html|OpenCV-Python Tutorials]]

[[https://docs.opencv.org/4.x/db/deb/tutorial_display_image.html| Started with Images]]