Image on Sawyer Zheng's Blog

Opencv

Fri, 25 Nov 2022 00:00:00 +0000

教程

中文：http://codec.wang/#/opencv/
英文： https://opencv-python-tutroals.readthedocs.io/en/latest/py_tutorials/py_setup/py_intro/py_intro.html#intro
bilibili 入门 python 接口视频：https://www.bilibili.com/video/BV19J411X7YG?p=1
codebind:
- 文章：http://www.codebind.com/category/python/opencv/
- 视频：
  - https://www.youtube.com/playlist?list=PLS1QulWo1RIa7D1O6skqDQ-JZ1GGHKK-K
Computer Vision 学习网站
- https://www.pyimagesearch.com/start-here/

资料搜集网址

知乎：https://www.zhihu.com/question/26881367/answer/815156603

安装

参考：

OpenCV not working properly with python on Linux with anaconda. Getting error…

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conda remove opencv
conda update conda
conda install --channel menpo opencv

conda remove opencv
conda install -c conda-forge opencv=4.1.0

pip install opencv-contrib-python

图像匹配 SIFT 方法

教程

参考：

Graphics Programing编程图形

Sat, 11 Sep 2021 00:00:00 +0000

教程

html graphics

矩形： (左上角顶点坐标为(x1,y1)，右下角顶点坐标为(x2,y2))
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<area shape="rect" coords="x1,y1,x2,y2" href=url>

圆形: (圆心坐标为(X1,y1)，半径为 r)

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<area shape="circle" coords="x1,y1,r" href=url>

多边形: (各顶点坐标依次为(x1,y1)、(x2,y2)、(x3,y3) ……)

image rendering ---- render image with python 图片处理

Wed, 17 Mar 2021 00:00:00 +0000

图片存储网站

postimages: Postimages — free image hosting / image upload
- 免费

工具

OpenCV
pillow
scikit-image
scipy.ndimage

工具比较

Python image processing libraries performance: OpenCV vs Scipy vs Scikit-Image

load and save

教程
- https://towardsdatascience.com/loading-and-saving-images-in-python-ba5a1f5058fb
- 打开方式和性能评估
  - https://towardsdatascience.com/what-library-can-load-image-in-python-and-what-are-their-difference-d1628c6623ad
三种方式
- PIL
- opencv –> np.ndarray
- matplotlib

imageMagick

Wed, 06 Jan 2021 00:00:00 +0000

安装

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sudo apt install imagemagick

报错

pdf security 报错

引用
- https://stackoverflow.com/a/53180170
方法

Well, I added

<policy domain="coder" rights="read | write" pattern="PDF" />

just before </policymap> in /etc/ImageMagick-7/policy.xml and that makes it work again, but not sure about the security implications of that.

截图

-crop

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 convert -density 200 ./one.pdf -quality 100 -colorspace gray -crop 500x500+500+500 "./one_300.jpg"

geometry 参数意义

参考

Computer Graphics

Mon, 03 Aug 2020 00:00:00 +0000

教程

曲线曲面：参数曲线、参数几何代数形式 https://blog.csdn.net/Jurbo/article/details/75046766

英语专业名词

CS184 教程

Lecture 0, Other notes

Instructor	导师，教育者
instructional	教学的，教育的
registrar	(大学)教务长，教务主任；登记员
Instructors and TAs	teacher assistants
roster	执勤名单；候选名单
class roster	老师的点名册（花名册）；名册
teaching staff	教职员；教师；教育工作者
user-programmable vertex engine
vertex	顶点
fragment shaders	像素着色器
as of	在……是
as of last semester
niggling issuses	微不足道的；（不严重却持续不断的）烦人的
being of importance	很重要
treate this assignment as being of utmost importance
piazza	(尤指意大利城镇中的) 广场;

Lecture 1, Course Overview

segment 1

spherical harmonic lighting	球谐光照
on the faculty of	职员之一；（院校）系里的成员
graphics image synthesis
rendering
create realistic images
ACM SIGGRAPH
program 3D computer graphics
OpenGL, which is a graphics API
the OpenGL shading language
a real time scene viewer
ray tracing	光线追踪算法
a little bit of a hint of the kinds of things
collage	拼贴画；收集品
reflections	反射
refractions	折射
glass spheres	玻璃球
chess boards
initial segment
it's really an intellectually, exciting and challenging field,
Pixar
1995 Toy Story by Pixar	first completely computer graphics movie
Lighting simulation
one very important area in computer graphics
computer graphics is really critical for visualization.
flight simulators
and so forth.	等等
digital visual media
of which computer graphics is an integral part
3D geometric models
Visual media are so prevalent
We have Flickr. YouTube. WebGL
Google earth
very realistic flythroughs of the real world.
Electronic publishing
Online gaming
is perhaps the biggest driver of games
3D printers and fabrication
we are now seeing a vast revolution
print real 3D objects, perhaps with realistic material properties
we can expect to see dramatic advances
new computing methods, new display technologies

Lighting simulation lighting simulation is important to create realistic simulations of how the interiors of buildings, interiors of rooms will look. How an automobile will look in an outdoor lighting environment. And computer graphics is used for all of these applications. It can be used for scientific visualization as well as medical visualization.
future So, what we have seen here is that computer graphics has numerous applications and it involves fundamental intellectual and technical challenges which make it one of the most exciting areas to study and I hope you will join us in this course.

Segement 2, Outline and Logistics

course logistics
go over some of the course logistics
3D graphics pipeline.
collaborators	合作者
humanoid motion	人形的
vibrant humanoid motion
assignment	任务
homework
assignment logistics
Logistics	组织，安排；
	后勤
rasterize	格栅化，点阵化
raytrace	光线追踪
workload	工作量
shaders
programmable shaders
our initial lecture on an overview and history.
was coined by	由……创造，铸造
a bank of	一堆……
a bank of LEDs
in the scene	场面，场景
presages	预兆
SuperPaint system really presages modern software technologies
alter images by cropping, scaling, compositing them.
add or remove objects.
Sports broadcasts
That's been a quick tour of 2D computer graphics.
Geometric modeling
Geometric modeling is the process of creating 3D geometry,
spline curves and surfaces	样条曲线
genus	属，类
spout	(容器的)嘴；水柱

3D graphics pipeline he graphics pipeline consists of 3 stages: modeling, animation and rendering.

svg 图片

Tue, 21 Jul 2020 00:00:00 +0000

Tutorial

svg, js and html
- http://www.petercollingridge.co.uk/tutorials/svg/interactive/javascript/#:~:text=To%20create%20elements%2C%20you%20need,methods%20of%20an%20SVG%20element.
- 示例代码：code-for-blog/svg-interaction/svg-and-js at master · petercollingridge/code-f…
SVG 教程 - 基础教程在线

在网页中使用 svg

插入方式

inline
external

SVG + JS

inline SVG

SVG 直接写在 html 中

pillow ---- PIL, pure python image rendering library 纯Python图像处理库

Thu, 29 Aug 2019 00:00:00 +0000

方法

Access a pixel

im.getpixel((row, col))

im.load()

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pixel_data = im.load()
pixel_data = [255,255,255]

im.putpixel((row, col), color)

numpy.array <–> PIL image

参考
- https://pillow.readthedocs.io/en/stable/reference/Image.html?highlight=numpy#PIL.Image.fromarray

PIL image –> numpy.array

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from PIL import Image
import numpy as np
im = Image.open('hopper.jpg')
arr = np.asarray(im)
arr01 = np.array(im)

np.array –> PIL Image

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im = Image.fromarray(a)