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Questions tagged [scanline]

47 questions
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Paint PNG image on other PNG

How to merge two PNG's together? I know that you can't use PNGObject.Draw because it doesn't copy alpha transaperncy (I am not sure but it doesn't work anyway) so custom procedure/function is needed. I didn't come with empty hands, I have this…
Little Helper
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Fast way of swapping Red/Blue bytes using ScanLine

Currently, I loop the Canvas.Pixels[] property and read each pixel on a canvas to swap Red/Blue bytes around (for specific reasons). However, it takes an average of 2 seconds per picture, and I have over 8,000 pictures I need to convert (overnight).…
Jerry Dodge
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Task about pairs of points and segments

Can you help me with problem? Given N <= 10^5 pairs of points, suppose they are written in array A, A[i][0] <= A[i][1]. Also, given M <= 10^5 pairs of segments, i-th pair given in form L_1[i], R_1[i], L_2[i], R_2[i]. For each pair of segments I need…
master
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Inverting a bitmap in Embarcadero C++Builder

The same problem happens in Borland C++Builder 6 and Embarcadero C++Builder 2010. When I try to invert an image, the form freezes for about 5 seconds and nothing happens. When I click again, the image is inverted within a blink of an eye, and again,…
hennep
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How can I get the whole polygon colored from this code?

Following is code of computer graphics concept Scanline algorithm but instead of polygon the other plane is getting colored how can I fix it? import javax.swing.*; import java.awt.*; public class CG4 extends JFrame { int m1 = -1,m2 = 0,m3 = 2; …
Prasenjit Hiwale
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problem with graphics.h in visual studio 2010

i am writing a simple program actually implementing scan line algorithm in C++ using Visual Studio 2010. but i am getting an error saying graphics.h file can not be found. can anybody tell me how to solve that problem? or any other way(without using…
Keshan
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How does this "common idiom" actually work?

Looking at documentation for golang's 2D slices and cannot understand the syntax used in the last example: func main() { XSize := 5 YSize := 5 // Allocate the top-level slice, the same as before. picture := make([][]uint8, YSize) //…
Jonathan
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Scanline algorithm: calculate x of edges

I'm trying to implement the scanline algorithm in Javascript. It looks like my calculation of x is wrong as the lines are to short or to long. These edges should be filled: This is how my scanline code fills it: My edge table has these…
Michael
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Scanline algorithm: how to calculate intersection points

I have to implement a scanline algorithm from our professor but I don't really understand how I get the intersection points from the scanline with a polygon. Here is the algorithm: I implemented my own polygon(with methods like paint(), contains()…
Peter
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scanline: finding intersection points

I want to fill a polygon with the scanline algorith. for this I have to know all points where the scanline comes in contact with the polygon. I wrote a loop for this, but its obviously not working (it never adds a point to the list which means it…
Peter
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How to scanline in 1D barcode region?

I need to scanline the region of interest for my image to check that it includes 1D barcode or not. Can anyone help me in how to implement this?Any relevant function ?
user3979
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Scanline Algorithm

I am stuck in the midway(or at the start you can say) while implementing scanline algo. I follow parity test i.e., for each scanline edgeCnt = 0; for each pixel on scanline (l to r) if (oldpixel->newpixel crosses edge) edgeCnt ++; // draw…
user1744119
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I wants to read rows of gray scale Image into an array of integer for processing in Qt

I have one Gray scale image, which I wants to read row by row and process( to find the median) I created one QImage by loading the file. Then I used scanline(x) to read the row. But I am getting some wrong values( hope values should be 0-256).…
Shibs
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scanline function in qimage class

I'm developing application for editing raster graphic. In this application I have to create scanline function which will do same thing as scanline function in QImage class. But I'm little confused with the way that scanline function works and with…
Mirzet
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Reading compressed EXR scan-line files by loading one scanline at a time into memory

I have some compressed EXR scan-line files that are unable to be read using minexr (shows error assert self.compr == 0x00, 'Compression not supported.'). Additionally, I want to read them one scanline at a time, so as to not overload memory. On the…
Ahmad Uzzam Masood
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