pixel | 易学教程

Offset gl_Position or gl_Vertex by pixels value

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问题 I have attribute contains pixels values. And i want to offset my gl_vertex with this attribute value. The problem is that my gl_vertex is in world units and the offset\attribute is in pixels. I can do it if i'm sending the screen size as uniforms and then convert the pixels to -1 to 1 values, and add it to the final gl_Position. But i don't want now to manage screen size events and sending it anyway every draw, every shader that i have. It there any way to do it with some matrix play, or

Offset gl_Position or gl_Vertex by pixels value

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OpenCV: How to iterate each pixel in a specific area of an image

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问题 I have an Image(see below) that is marked by two parallel green lines. This image is read in a OpenCV Mat in C++, the slope of green lines and their distances to the image center are already known. Now I want to iterate all the pixels in the area between these two green lines. How can i solve this problem? It will be very helpful, if somebody can give me a code example. Many thanks. 回答1: The formula for a slope is the following: y = mx + b Since you have two of them you should have two slope

c++ read pixels with GetDIBits()

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问题 I'm trying to create a function which is equivalent to the windows API GetPixel() function, but I want to create a bitmap of my screen and then read that buffer. This is what I've got (Mostly copy pasted from google searches), when I run it it only prints out 0's. I think I've got most of it right, and that my issue is that I don't know how to read the BYTE variable. So my question is, what do I need to do in order to get it to print out some random colors (R,G or B) with my for loop?

Kinect depth conversion from mm to pixels

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问题 Does anybody knows how many pixels correspond for each millimeter of depth value in images taken from kinect for xbox360? I'm using the standard resolution and settings... Thanks! 回答1: 1 pixel corresponds to a number of millimiters that depends on the depth value of that pixels (i.e. its level of gray). The simplest way you can get the distance between two pixels in a depth image is to convert those pixels (which are expressed in Depth Space ) in real world coordinates (i.e. in Skeleton Space

Image Magick / Detect colors contained on a image

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问题 What would be the simple process that would gives an array of the colors contained in an image ? 回答1: ImageMagick's "convert" command can generate a histogram. $ convert image.png -define histogram:unique-colors=true -format %c histogram:info:- 19557: ( 0, 0, 0) #000000 gray(0,0,0) 1727: ( 1, 1, 1) #010101 gray(1,1,1) 2868: ( 2, 2, 2) #020202 gray(2,2,2) 2066: ( 3, 3, 3) #030303 gray(3,3,3) 1525: ( 4, 4, 4) #040404 gray(4,4,4) . . . Depending on your language of choice and how you want the

Working in a BufferedImage's int[] pixels array

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问题 When working with BufferedImage using the setRGB and getRGB methods, I noticed two things: the setRGB and getRGB methods can be incredibly slow on some systems (as much as two orders of magnitude slower than modifiyng the int[] array). there are no guarantee that a getRGB following a setRGB will give back the same pixel you passed This last point is basically pretty clear from the JavaDoc of setRGB , which states: ...For images with an IndexColorModel, the index with the nearest color is

javascript ImageData typed array read whole pixel?

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问题 So there is are a lot of examples on how to write an entire pixel from a Uint32Array view of the ImageData object. But is it possible to read an entire pixel without incrementing the counter 4 times? From hacks.mozilla.org, writing an rgba pixels looks like this . var imageData = ctx.getImageData(0, 0, canvasWidth, canvasHeight); var buf = new ArrayBuffer(imageData.data.length); var buf8 = new Uint8ClampedArray(buf); var data = new Uint32Array(buf); for (var y = 0; y < canvasHeight; ++y) {

blurring an image using PIL in python

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问题 I have been trying to blur an image using the PIL. from what I know i need to copy the image, and then change every pixel to the average of the pixels surrounding him, from the original picture. so I didn't get really far, i'm using python 3.3x from PIL import Image img = Image.open("source") im = Image.copy(img) I know how to use putpixe, and get a pixel's data, but I can't figure out how to get the average of the pixels around. Thanks in advance for the help! 回答1: You can just do: blurred

MFC中的CDC 绘图(2)

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．面色（刷）在Windows中，面状图必须用刷(brush)来填充，所以面色是由刷色来确定的。MFC中的刷类为CBrush（它也是CGDIObject的派生类），刷的创建与使用的步骤与笔的相似。构造函数有4个： CBrush( ); // 创建一个刷的空对象 CBrush( COLORREF crColor ); // 创建颜色为crColor的实心刷 CBrush( int nIndex, COLORREF crColor ); // 创建风格由nIndex指定且颜色为crColor的条纹(hatch孵化)刷，其中nIndex可取条纹风格(Hatch Styles)值：符号常量数字常量风格 HS_HORIZONTAL 0 水平线 HS_VERTICAL 1 垂直线 HS_FDIAGONAL 2 正斜线 HS_BDIAGONAL 3 反斜线 HS_CROSS 4 十字线(正网格) HS_DIAGCROSS 5 斜十字线(斜网格) CBrush( CBitmap* pBitmap ); // 创建位图为pBitmap的图案刷如：pDC->FillRect( &rect, new CBrush( RGB(r, g, b) ) ); 与构造函数相对应，有多个创建不同类型刷的成员函数： BOOL CreateSolidBrush( COLORREF crColor );