dll - Matlab : convert a uint8 matrix (made of 0 and 1) to export as binary data -


my problem :

i have 1920x1080 uint8 matrix made of zeros , ones in matlab. let's call "image". want exporting image binary, meaning each byte of output should contain information of 8 pixels. in short : want 1bit per pixel.

if understood well, can't convert binary in matlab "logical(...)" function because logicals still stored 8bits in memory (although value can 0 or 1 of course).

why need ?

i want export image through ".dll" accepts image in specific format (for faster transfer usb device).

the format of output :

here ".dll" expecting : (1 byte = 8 consecutive bits)

  • the image reads left right, top bottom (usual convention)
  • every byte of data represents 8 pixels, e.g.
    • (1st byte) = [px8|px7|...|px1]
    • (2nd byte) = [px16|px15|...|px9]
    • and on.
  • note every line of image has 1920 pixels (which can divided 8, 1920/8=240) there 240 bytes per line of image

my question :

how should reorganize data ? guess depends on how matlab stores data in memory (and sends ".dll")? have no idea that...

here code use if no memory tricks expected. idea take every 8 pixels , build 8bit value them in correct order, e.g. these pixel values (1 0 0 0 0 0 1 0) become 65 (expressed in decimal). send new matrix ".dll" , hope works.

finalimage=zeros(1920,240); % 240 = number of bytes per line myrow=1:1080     mybyte=1:240          currentbyte=0;         mybit=0:7             currentbyte=currentbyte + 2^(7-mybit) * image(myrow, 1 + 8*(mybyte-1) + mybit );         end         finalimage(myrow, mybyte) = currentbyte;     end end

solution :

with of divakar, forgot loops , preferred simple code:

% convert every 8 pixels (values 0 or 1) in row 1 single pixel (value 0 255) % (bi2de option used : "left significant bit" in case) % (make sure width of image multiple of 8)  vect=bi2de(reshape(input_img',8,[])','left-msb'); img=reshape(vect,img_width/8,[])';

this solution might helpfull else, 1 day or !

assuming input_image input binary matrix , output_dll_filepath path output dll file, may try cell-array approach -

code

%// convert 8-bit data [m,n] = size(input_image) cell1 = mat2cell(input_image,ones(1,m),8.*ones(1,n/8)) output_data = cellfun(@(x) bin2dec(num2str(fliplr(x),'%1d')),cell1); output_data = reshape(output_data',[],1)  %// write 8-bit data dll file fid = fopen(output_dll_filepath , 'w'); fwrite(fid, output_data, 'uint8'); fclose(fid);

or use -

output_data = bin2dec(fliplr(num2str(reshape(input_image',8,[])','%1d')))

and use write 8-bit data dll file used earlier was.

or -

fid = fopen(output_dll_filepath , 'w'); fwrite(fid, reshape(input_image',8,[]), 'ubit1'); fclose(fid);

Comments

Post a Comment

Popular posts from this blog

commonjs - How to write a typescript definition file for a node module that exports a function? -

consider, toml node module can use: // toml.d.ts declare module toml { export function parse(value:string):any; } declare module "toml" { export = toml; } then: /// <reference path="../../../../../defs/toml/toml.d.ts"/> import toml = require('toml'); toml.parse(...); however, node module export single function, such 'glob' ( https://github.com/isaacs/node-glob ). the node usage of module be: var glob = require("glob") glob("*.js", {}, callback(err, files) { ... }); you'd naively expect this: // glob.d.ts declare function globs(paths:string, options:any, callback:{(err:any, files:string[]):void; ...but because typescripts 'import' semantics bit strange, seems can use 'import .. = require()' statement alias modules . trying call: /// <reference path="../../../../../defs/glob/glob.d.ts"/> import blog = require('glob'); results in: error ts2072: mod
Read more

openid - Okta: Failed to get authorization code through API call -

i'm integrating okta own idp server using okta's api. i'm implementing authorization code flow following steps below: in own server, use /api/v1/authn endpoint sessiontoken. use sessiontoken obtain authorization calling endpoint: /oauth2/v1/authorize?client_id=" + clientid + "&sessiontoken=" + sessiontoken + "&response_type=code&response_mode=query&scope=openid&redirect_uri=" + redirecturl + "&state=evanyang&nonce=" it's supposed return response status code 302 , location header containing redirect url code value. however, keep getting response status code 200 , without location header, html body saying "you using unsupported browser." , "javascript disabled on browser." according api documentation: http://developer.okta.com/docs/api/resources/oidc.html#authentication-request , sessiontoken parameter sufficient this: an okta one-time sessiontoken. allows api-based
Read more

thorough guide for profiling racket code -

did googling ("racket profiling", "racket measure performance"), didn't find , there no examples in docs. did google "profile" search on htdp - no luck. (profile (f ...)) output isn't obvious other small snippets. ideally want python's python -m cprofile usage examples. when search "python profiling", both duckduckgo , google give top result: 26.4. python profilers . (although scanned quickly, seems more of reference "thorough usage guide" examples. if had else in mind, perhaps please link that?) the equivalent racket documentation be: profile: statistical profiler . a usage example: #lang racket (require profile) (profile-thunk (thunk (function-to-profile arg0 arg1) )) here (thunk e) convenience (lambda () e) . bigger example: #lang racket (module mod racket (provide f) (define (f) (for/list ([i 10000]) i))) (require (prefix-in mod: 'mod)) (define (f) (for ([i 10000
Read more