image processing - How to convert a jpg to yuv in C? -

-

even though question of nature sounds similar, having problems in converting jpg image yuv in c (without using opencv).

this have understood of now, how solve problem :

  1. identify structure of file formats jpg , yuv. i.e each byte in file contains. think jpg format looks like.
  2. with above structure tried read jpg file , tried decipher 18th , 19th bytes. did type cast them both char , int don`t meaningful values width , height of image.

  3. once have read these values, should able convert them jpg yuv. looking @ resource.

  4. appropriately, construct yuv image , write (.yuv) file.

kindly me pointing me appropriate resources. keep updating progress on post. in advance.

based on https://en.wikipedia.org/wiki/yuv#y.27uv444_to_rgb888_conversion

yuv conversion

decoding jpeg, in pure c without libraries ... following code straightforward ...

https://bitbucket.org/halicery/firerainbow-progressive-jpeg-decoder/src

assuming have jpeg decoded rgb using above or library (using library easier).

int width = (width of image); int height = (height of image); byte *mydata = (pointer rgb pixels); byte *cursor; size_t byte_count = (length of pixels .... i.e. width x height x 3); int n; (cursor = mydata, n = 0; n < byte_count; cursor += 3, n += 3)  {     int red = cursor[0], green = cursor[1], blue = cursor[2];     int y = 0.299 * red + 0.587 * green + 0.114 * blue;     int u = -0.147 * red + -0.289 * green + 0.436 * blue;     int v = 0.615 * red + -0.515 * green + -0.100 * blue;      cursor[0] = y, cursor[1] = u, cursor[2] = v; }  // @ point, entire image has been converted yuv ...

and write file ...

file* fout = fopen ("myfile.yuv, "wb");  if (fout) {     fwrite (mydata, 1, byte_count, fout);     fclose (fout); }

Comments

Post a Comment

Popular posts from this blog

python - pip install -U PySide error -

-
does know how avoid following error when running pip install -u pyside per official website instructions here: https://pypi.python.org/pypi/pyside/#installing-pyside-on-a-mac-os-x-system note have done brew install qt successfully. you using pip version 7.0.3, version 7.1.2 available. should consider upgrading via 'pip install --upgrade pip' command. collecting pyside using cached pyside-1.2.4.tar.gz installing collected packages: pyside running setup.py install pyside complete output command /applications/anaconda/bin/python -c "import setuptools, tokenize;__file__='/private/var/folders/dy/ttgqhqqx3g9bsbsnqnxsk2z80000gq/t/pip-build-cpxemt/pyside/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record /var/folders/dy/ttgqhqqx3g9bsbsnqnxsk2z80000gq/t/pip-0r7hri-record/install-record.txt --single-version-externally-managed --compile:
Read more

arrays - C++ error: a brace-enclosed initializer is not allowed here before ‘{’ token -

-
simple question: i'm trying initialize array within c++ class declaration: using namespace std; #include <string> class myclass{ public: string myarray[] = {"a","b","c"}; }; and i'm getting error: error: brace-enclosed initializer not allowed here before ‘{’ token no, without complied c++11 compiler, cannot initialize member array in declaration. have initialize array member in constructor. , don't use open array if know number of elements initialize array.
Read more

cytoscape.js - How to add nodes to Dagre layout with Cytoscape -

-
i trying add nodes dagre graph through cityscape.js. problem nodes not painted. code have: cy.add({ group: "nodes", data: { id:"n0",name:"n0",weight: 75 }, }); $.ajax(url).done(function(jsontree){ var newnodes=[]; for(var i=1;i<6;i++){ //var child = jsontree.result[i]; newnodes.push( { group: "nodes", data: { id: "n"+i, name:"n"+i}}, { group: "edges", data: { id: "e"+i, source: "n0", target: "n"+i } } ); } cy.add(newnodes); any ideas? have used loaded function reload graph not work. not know if have use specific function reload graph. thank in advance. you need add positions new nodes. cytoscape.js docs : it important note positions of newly added nodes must defined when calling cy.add(). nodes can not placed in graph without valid position — otherwise not displayed. yo
Read more