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Questions tagged [raster-image]

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1 answer
14 views

Clarification on PPI

I wanted to convert a chart rendered by canvas element to an image file so that the user can download it. But the official HTML docs say that: The created image data will have a resolution of 96dpi ...
0 votes
0 answers
16 views

PPM P3 has different pixel values but appears to be in uniform color

I have generated a PPM P3 file using C++. Even though the pixels are different, when I open the file in a text editor, it appears to be of only one color in my preview program. What is the problem? <...
0 votes
1 answer
85 views

How to identify images with similar content?

There's a set of pictures that if you take them literally, they're different. That is, there can be two images of the same thing among them, only in different hue. In addition, among these two, there ...
0 votes
0 answers
25 views

Animated bitmaps with 2 colours only

I want to create an animated GIF, but instead of 8-bit 256 colours, my data is comprised of binary bitmaps of black/white pixels. Can GIF accommodate this, or are pixels in GIF always 8-bit indices? I ...
0 votes
1 answer
145 views

Is it possible to convert Polar to Cartesian coordinates and map result to an image using opengl?

Is it possible to convert Polar to Cartesian coordinates and map result to an image? I want to get the output same as the distort depolar 0 from image magick. https:...
1 vote
1 answer
338 views

How to use maximum resolution (pixel density) with OpenGL in MS Windows

CodeBlocks offers an example program in C, that uses OpenGL. It draws a single multicoloured rotating triangle. I have been building on this example. I am a novice in C and in OpenGL. I believe that I ...
0 votes
1 answer
446 views

Screen Space anti aliasing?

I have the following challenge. I am given a black and white image with rasterized lines. Given this input, I want to extend the edges to cover more than one pixel and antialias the edges. My first ...
3 votes
1 answer
766 views

Wrong color in .ppm file

I'm going through the rasterizer tutorial from Scratchapixel, but I encountered a problem with the generation of the .ppm file. Since something was off, I reduced the example to the bare minimum, so I ...
0 votes
0 answers
43 views

How to render a rotated raster image with lesser aliasing

I am wondering about techniques for rendering a rotated and or scaled raster image. Currently I use the following algorithm Render everything at double resolution and store the result in ...
1 vote
1 answer
874 views

How to calculate spatial frequency of an image just in one direction?

FFT spectra is not what is needed; what I need is a histogram showing which frequencies are there in image in horizontal direction, and which one is dominant Such spatial frequency is usually known ...
2 votes
0 answers
62 views

Normalization technique to increase spread of data in rgb space

I am visualizing a dataset. My technique is to encode the data into a rgb image with the channel range [0, 255]. The data clusters in a narrow range relative to [0, 255], however, so I'm not getting ...
2 votes
1 answer
364 views

Image saved as DDS with 16f format in photoshop has strange FOURCC text

I am analyzing the hex code for DDS files which are compressed via Nvidia's dds plugin in photoshop. I noticed something strange when having a 16 bit float file. This is the dialog: When I look at ...
0 votes
0 answers
64 views

How is the image reconstruction filter on the path space defined in terms of the filter on the raster space?

Say we have a image reconstruction filter $h:R\to\mathbb R$ defined on the raster space $[0,w]\times[0,h]$, where $w,h\in\mathbb N$ define the width and height of the image plane in pixels, ...
1 vote
0 answers
298 views

Deskewing and Cropping Scans using ImageMagick

Attempting to deskew and crop scans of a CD booklet using ImageMagick. Here's one image which I've been using as an example on which to build my one-liner - https://mega.nz/#!jIQD3aqC!PbjG4_Xaq-...
1 vote
2 answers
858 views

How to generate the stereographic projection of a 3D model

Given a 3D model, is there a way to stereographically project it to a 2D image? In particular, I would only need a little more than half the model (the lower half) to be mapped to the plane (mapping ...
4 votes
1 answer
1k views

Triangulated model rasterization: light-weight Python library

I have a 3D model, which consists of ~50 thousand vertices and 100 thousand triangles. Format is: there's array of vertices' coordinates and array of triangles, which has numbers of vertices (e.g., [1,...
7 votes
2 answers
5k views

Image rotation using FFT

I'm not sure how practical this might be but is it possible to use Fast Fourier Transform to rotate a raster image? To be honest, I never really understood FFT, but I saw it being used for JPEG, for ...
6 votes
2 answers
160 views

Is there a image-format that support an array per pixel?

For a project dealing with deep semantic labeling of images I need a format that supports arrays of arbitrary length for each pixel of the image. The array is an array of integers. Which image ...
3 votes
1 answer
2k views

Image rotation algorithm

I would like to rotate a raster image by an arbitrary angle. I don't really care for speed: the rotation should be of highest quality possible. Could someone please suggest a suitable algorithm? I'm ...
3 votes
2 answers
580 views

How is Raster and Random Scan Display different?

Raster scan display forms an image with pixel whereas a Random scan display works with Geometric primitives, but even a geometric primitve( a line) is made up of pixels so what is the difference?
3 votes
0 answers
61 views

Compute angles and thereby endpoints in a raster grid?

I am at the moment having some issues with computing an endpoint in a raster grid that is also a valid position in a graph. I am trying to draw a line between these two points, but as the point I am ...
5 votes
1 answer
2k views

Draw angles lines in raster graphics using bresenham line algorithm

I at the moment trying to draw some angled lines using bresenham line algorithm which can circulate a 2d array of size 21x21, as a line angled from 0 - 2pi. So the idea is that the program has to ...
3 votes
0 answers
65 views

Draw lines angled from 0 to 2 pi in a raster grid [duplicate]

I am trying to draw an angled line in a raster grid. The idea is to create a function that given a start point, a length and an angle, would give me the pixel positions that combined would give me a ...