Reading and Writing of Images

OpenCV provides a wide range of functions for image processing, including reading and writing images.

OpenCV.jl provides 2 ways to read and write images

1. OpenCV native api
2. FileIO.jl api

OpenCV provides imread and imwrite, while FileIO privides load and save for similar functionalities

Reading Images

using OpenCV

img_path = "/path/to/image"
img = OpenCV.imread(img_path)

with FileIO

using OpenCV, FileIO

img_path = "/path/to/image"
img = load(img_path)

in both cases img has same data. Both methods accept same reading flags^{[imreadflags]}.

using OpenCV

img_path = "/path/to/image"
flag = OpenCV.IMREAD_UNCHANGED 
img = OpenCV.imread(img_path, flag)

with FileIO

using OpenCV, FileIO

img_path = "/path/to/image"
flag = OpenCV.IMREAD_UNCHANGED 
img = load(img_path, flag)

Writing Images

using OpenCV

img = rand(UInt8, 1000, 1000) |> OpenCV.Mat
img_path = "/path/to/image"
OpenCV.imwrite(img_path, img)

with FileIO

using OpenCV, FileIO

img = rand(UInt8, 1000, 1000) |> OpenCV.Mat
img_path = "/path/to/image"
save(img_path, img)

Both methods accept same writing flags^{[imwriteflags]}.

using OpenCV

img = rand(UInt8, 1000, 1000) |> OpenCV.Mat
img_path = "/path/to/image"
flag = Int32[OpenCV.IMWRITE_JPEG_QUALITY, 100]
OpenCV.imwrite(img_path, img, flag)

with FileIO

using OpenCV, FileIO

img = rand(UInt8, 1000, 1000) |> OpenCV.Mat
img_path = "/path/to/image"
flag = Int32[OpenCV.IMWRITE_JPEG_QUALITY, 100]
save(img_path, img, flag)

Displaying Images

When working with images, it's obviously helpful to be able to look at them. If you use Julia through Pluto, VSCode, or IJulia, images should display automatically.

Preview from Pluto.jl

OpenCV.imshow method display image on Qt window.

Plots.jl To-do

Makie.jl To-do

Notes