php - fabric js or imagick remove white from image -

-

i got situation hard me search on google , explain.

our company prints photos on aluminium , give our customers 2 choices.

  1. the first choice print pictures on aluminium gave picture us, if picture has white background picture gets printed white background. easy that.

  2. the second option can print picture without using white. instead of "white values" (<- best can come explain) being printed leave transparent.

i know there removewhite filter in fabric js can replace white areas transparent ones. not need. need fabric js filter, imagemagick thing or other php or js solution can turn "white value" of pixel transparent. know stuff may sounds vague guys, let me try explain way:

  • if come across white pixel need make transparent.

  • if come across grey pixel, need turn combination of white , black combination of transparent , black.

  • if come cross coloured pixel, need turn "white value" makes light turn transparent.

here before , after example of filter/effect try accomplish:

before:

after:

please don't hesitate ask me if don't understand i'm asking for.

i got work. using factors yuv color space, create fabric js image filter.

it lot of trial-and-error result looking for. therefore don't have (detailed) description of how works. know have used yuv factors brightness of (rgb) colours.

for (i = 0; < ilen; i++) {     (j = 0; j < jlen; j++) {       index = (i * 4) * jlen + (j * 4);       var yuv = {};       yuv.r = data[index] / 255 * 1 * 0.299;            yuv.g = data[index + 1] / 255 * 1 * 0.587; //we use yuv formula constants       yuv.b = data[index + 2] / 255 * 1 * 0.114; //to try catch y (brightness)       yuv.y = yuv.r + yuv.g + yuv.b;             //you can tweak       data[index + 3] = 350 - (yuv.y / 1 * 255); //by changing first number after "=" on line!     } }

somehow messing 350 on last line can alter transparency factor.

sorry not being able explain more how fabric filter works.


Comments

Post a Comment

Popular posts from this blog

c++ - llvm function pass ReplaceInstWithInst malloc -

-
#include "llvm/pass.h" #include "llvm/ir/module.h" #include "llvm/ir/function.h" #include "llvm/support/raw_ostream.h" #include "llvm/ir/legacypassmanager.h" #include "llvm/ir/instrtypes.h" #include "llvm/transforms/ipo/passmanagerbuilder.h" #include "llvm/ir/irbuilder.h" #include "llvm/transforms/utils/basicblockutils.h" using namespace llvm; namespace { struct replacepass : public functionpass { static char id; replacepass() : functionpass(id) {} virtual bool runonfunction(function &f) { allocainst* insttoreplace = ??? basicblock::iterator ii(insttoreplace); replaceinstwithinst(insttoreplace->getparent()->getinstlist(), ii, new allocainst(type::int32ty, 0, insttoreplace)); return true; } }; } char replacepass::id = 0; static void registerreplacepass(const passmanagerbuilder &, legacy::passmanagerbase &pm) { pm.add(new re
Read more

java.lang.NoClassDefFoundError When Creating New Android Project -

-
i've tried installing (and re-installing) android studio several times now, , each time, studio isn't able create new android project. when attempt initial android studio window (ie. basic 'create', 'open', 'import' etc options), i'm asked of questions in wizard, brief progress dialog, followed nothing @ all. if open incomplete project process creates choosing 'open' list, can try choosing create new android project menu. this has same issue, error message in output console time... java.lang.noclassdeffounderror: com/sun/xml/internal/bind/v2/model/annotation/annotationreader (wrong name: com/sun/xml/internal/bind/v0/model/qnnotation/annotationreader) note: when installed android studio, installed incompatible jdk (1.8, not 1.7). have had go default project settings change jdk uses 1.8. does know how can avoid this? there place should downloading jxb classes? missing in java paths? this appears have been caused cor
Read more

Decoding a Python 2 `tempfile` with python-future -

-
i'm attempting write python 2/3 compatible routine fetch csv file, decode latin_1 unicode , feed csv.dictreader in robust, scalable manner. for python 2/3 support, i'm using python-future including imporing open builtins , , importing unicode_literals consistent behaviour i'm hoping handle exceptionally large files spilling disk, using tempfile.spooledtemporaryfile i'm using io.textiowrapper handle decoding latin_1 encoding before feeding dictreader this works fine under python 3. the problem textiowrapper expects wrap stream conforms bufferediobase . unfortunately under python 2, although have imported python 3-style open , vanilla python 2 tempfile.spooledtemporaryfile still of course returns python 2 cstringio.stringo , instead of python 3 io.bytesio required textiowrapper . i can think of these possible approaches: wrap python 2 cstringio.stringo python 3-style io.bytesio . i'm not sure how approach - need write such wrapper or 1 ex
Read more