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improved steganography functions

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rlx 2011-09-08 12:27:40 +00:00
commit 1b4591dcbe
3 changed files with 47 additions and 14 deletions
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30
source/Ox.Image/Ox.Image.js
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@ -27,7 +27,7 @@ Ox.load.Image = function(options, callback) {
function getCapacity(bpb) {
var capacity = 0;
that.forEach(function(rgba) {
capacity += rgba[3] == 255 ? bpb / 8 : 0;
capacity += rgba[3] == 255 ? bpb * 3/8 : 0;
});
return capacity;
}
@ -167,21 +167,29 @@ Ox.load.Image = function(options, callback) {
var i = index + c;
Ox.forEach(bits, function(bit) {
if (mode < 1) {
bin += Ox.sum(Ox.range(8).map(function(b) {
return self.data[i] & 1 << b;
bin += Ox.sum(Ox.range(8).map(function(bit) {
return +!!(self.data[i] & 1 << bit);
})) % 2;
} else {
bin += +!!(self.data[i] & i << bit);
bin += +!!(self.data[i] & 1 << bit);
}
/*mode > 0 &&*/ Ox.print(bin)
// /*mode > 0 &&*/ Ox.print(bin)
if (bin.length == 8) {
str += Ox.char(parseInt(bin, 2));
bin = '';
if (str.length == len) {
if (++done == 1) {
len = Ox.decodeBase256(str);
Ox.print("LEN", len)
if (len + 4 > getCapacity(1)) {
Ox.print(Ox.map(str, function(chr) {
return Ox.pad(chr.charCodeAt(0).toString(2), 8);
}).join(' '))
Ox.print("LEN", len, getCapacity(bits.length), bits, xy, c)
Ox.print(Ox.range(index).map(function(i) {
return that.pixel(i, 0).map(function(px, j) {
return j < 4 ? Ox.pad(px.toString(2), 8) : null;
}).join(',')
}).join('\n'))
if (len + 4 > getCapacity(bits.length)) {
error('decode');
}
str = '';
@ -250,16 +258,16 @@ Ox.load.Image = function(options, callback) {
mode < 1
// If the number of bits set to 1, mod 2
? Ox.sum(Ox.range(8).map(function(bit) {
return self.data[i] & 1 << bit;
return +!!(self.data[i] & 1 << bit);
})) % 2
// or the one bit in question
: self.data[i] & 1 << bit
: +!!(self.data[i] & 1 << bit)
// is not equal to the data bit
) != bin[b++]) {
// then flip the bit
self.data[i] ^= 1 << bit;
}
})
});
/*
if (mode < 1) {
if (Ox.sum(Ox.range(8).map(function(bit) {
@ -406,7 +414,7 @@ Ox.load.Image = function(options, callback) {
};
that.pixel = function(x, y, val) {
var index = getIndex(x, y);
var i = getIndex(x, y);
if (!val) {
return Ox.range(4).map(function(c) {
return self.data[i + c];