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Fix #10: Use of saturate function almost always causes a crash.

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saturate: fix possible division by 0
SaturateImage: fix: had two 'image' members, one inherited, one nullptr, which caused a crash

git-svn-id: svn://svn.code.sf.net/p/magicseteditor/code/trunk@1458 0fc631ac-6414-0410-93d0-97cfa31319b6
This commit is contained in:
twanvl
2010-07-22 00:29:35 +00:00
parent 55599011b4
commit 66bf7c8521
3 changed files with 31 additions and 37 deletions
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src/gfx/image_effects.cpp
+25 -12
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@@ -13,13 +13,32 @@
// ----------------------------------------------------------------------------- : Saturation
void saturate(Image& image, double amount) {
if (amount == 0) return; // nothing to do
Byte* pix = image.GetData();
Byte* end = pix + image.GetWidth() * image.GetHeight() * 3;
if (amount > 0) {
amount = min(amount,0.99);
int factor = int(256 * amount);
int div = 768 - 3 * factor;
// the formula for saturation is
// rgb' = (rgb - amount * avg) / (1 - amount)
// if amount >= 1 then this is some kind of inversion
// if amount > 0 then use formula directly
// if amount < 0 then de-saturate instead:
// rgb = rgb' + -amount*avg - -amount*rgb'
// = rgb' * (1 - -amount) + -amount*avg
// if amount < -1 then we are left with just the average
int factor = int(256 * amount);
if (factor == 0) {
return; // nothing to do
} else if (factor == 256) {
// super crazy saturation: division by zero
// if we take infty to be 255, then it is a >avg test
while (pix != end) {
int r = pix[0], g = pix[1], b = pix[2];
pix[0] = r+r > g+b ? 255 : 0;
pix[1] = g+g > b+r ? 255 : 0;
pix[2] = b+b > r+g ? 255 : 0;
pix += 3;
}
} else if (factor > 0) {
int div = 768 - 3 * factor;
assert(div > 0);
while (pix != end) {
int r = pix[0], g = pix[1], b = pix[2];
int avg = factor*(r+g+b);
@@ -28,14 +47,8 @@ void saturate(Image& image, double amount) {
pix[2] = col((768*b - avg) / div);
pix += 3;
}
} else if (amount < -0.99) {
while (pix != end) {
int r = pix[0], g = pix[1], b = pix[2];
pix[0] = pix[1] = pix[2] = (r+g+b)/3;
pix += 3;
}
} else {
int factor1 = int(256 * -amount);
int factor1 = -factor;
int factor2 = 768 - 3*factor1;
while (pix != end) {
int r = pix[0], g = pix[1], b = pix[2];