utilitaires pour manipuler des images

Files
file	color.h
file	image.h

Classes
struct	Color
	representation d'une couleur (rgba) transparente ou opaque. More...
class	Image
	representation d'une image. More...

Functions
Color	Black ()
	utilitaire. renvoie une couleur noire.
Color	White ()
	utilitaire. renvoie une couleur blanche.
Color	Red ()
	utilitaire. renvoie une couleur rouge.
Color	Green ()
	utilitaire. renvoie une couleur verte.
Color	Blue ()
	utilitaire. renvoie une couleur bleue.
Color	Yellow ()
	utilitaire. renvoie une couleur jaune.
Color	operator+ (const Color &a, const Color &b)
Color	operator- (const Color &a, const Color &b)
Color	operator- (const Color &c)
Color	operator* (const Color &a, const Color &b)
Color	operator* (const Color &c, const float k)
Color	operator* (const float k, const Color &c)
Color	operator/ (const Color &a, const Color &b)
Color	operator/ (const float k, const Color &c)
Color	operator/ (const Color &c, const float k)
Color	operator+ (const float k, const Color &c)
Color	operator+ (const Color &c, const float k)
Color	srgb (const Color &color, const float g=float(2.2))
	transformation couleur : rgb lineaire vers srgb
Color	linear (const Color &color, const float g=float(2.2))
	transformation couleur : srgb vers rgb lineaire
Color	abs (const Color &color)
Image	read_image (const char *filename, const bool flipY=true)
	charge une image .bmp .tga .jpeg .png ou .hdr
bool	write_image (const Image &image, const char *filename, const bool flipY=true)
	enregistre une image au format .png
bool	write_image_png (const Image &image, const char *filename, const bool flipY=true)
	enregistre une image au format .png
bool	write_image_bmp (const Image &image, const char *filename, const bool flipY=true)
	enregistre une image au format .bmp
bool	write_image_hdr (const Image &image, const char *filename, const bool flipY=true)
	enregistre une image au format .hdr
bool	write_image_preview (const Image &image, const char *filename, const bool flipY=true)
	raccourci pour write_image_png(tone(image, range(image)), "image.png")
Image	srgb (const Image &image)
	transformation couleur : rgb lineaire vers srgb
Image	linear (const Image &image)
	transformation couleur : srgb vers rgb lineaire
float	range (const Image &image)
	evalue l'exposition d'une image.
Image	tone (const Image &image, const float saturation)
	correction de l'exposition d'une image + transformation gamma.

Detailed Description

Function Documentation

Black()

Color Black

(

)

utilitaire. renvoie une couleur noire.

Definition at line 18 of file color.cpp.

{
    return Color(0, 0, 0);
}

White()

Color White

(

)

utilitaire. renvoie une couleur blanche.

Definition at line 23 of file color.cpp.

{
    return Color(1, 1, 1);
}

Red()

Color Red

(

)

utilitaire. renvoie une couleur rouge.

Definition at line 28 of file color.cpp.

{
    return Color(1, 0, 0);
}

Green()

Color Green

(

)

utilitaire. renvoie une couleur verte.

Definition at line 33 of file color.cpp.

{
    return Color(0, 1, 0);
}

Blue()

Color Blue

(

)

utilitaire. renvoie une couleur bleue.

Definition at line 38 of file color.cpp.

{
    return Color(0, 0, 1);
}

Yellow()

Color Yellow

(

)

utilitaire. renvoie une couleur jaune.

Definition at line 43 of file color.cpp.

{
    return Color(1, 1, 0);
}

operator+() [1/3]

Color operator+	(	const Color &	a,
		const Color &	b
	)

Definition at line 73 of file color.cpp.

{
    return Color(a.r + b.r, a.g + b.g, a.b + b.b, a.a + b.a);
}

operator-() [1/2]

Color operator-	(	const Color &	a,
		const Color &	b
	)

Definition at line 83 of file color.cpp.

{
    return a + (-b);
}

operator-() [2/2]

Color operator-

(

const Color &

c

)

Definition at line 78 of file color.cpp.

{
    return Color(-c.r, -c.g, -c.b, -c.a);
}

operator*() [1/3]

Color operator*	(	const Color &	a,
		const Color &	b
	)

Definition at line 88 of file color.cpp.

{
    return Color(a.r * b.r, a.g * b.g, a.b * b.b, a.a * b.a);
}

operator*() [2/3]

Color operator*	(	const Color &	c,
		const float	k
	)

Definition at line 98 of file color.cpp.

{
    return k * c;
}

operator*() [3/3]

Color operator*	(	const float	k,
		const Color &	c
	)

Definition at line 93 of file color.cpp.

{
    return Color(c.r * k, c.g * k, c.b * k, c.a * k);
}

operator/() [1/3]

Color operator/	(	const Color &	a,
		const Color &	b
	)

Definition at line 103 of file color.cpp.

{
    return Color(a.r / b.r, a.g / b.g, a.b / b.b, a.a / b.a);
}

operator/() [2/3]

Color operator/	(	const float	k,
		const Color &	c
	)

Definition at line 108 of file color.cpp.

{
    return Color(k / c.r, k / c.g, k / c.b, k / c.a);
}

operator/() [3/3]

Color operator/	(	const Color &	c,
		const float	k
	)

Definition at line 113 of file color.cpp.

{
    float kk= 1 / k;
    return kk * c;
}

operator+() [2/3]

Color operator+	(	const float	k,
		const Color &	c
	)

Definition at line 119 of file color.cpp.

{
    return Color(k + c.r, k + c.g, k + c.b, k + c.a);
}

operator+() [3/3]

Color operator+	(	const Color &	c,
		const float	k
	)

Definition at line 124 of file color.cpp.

{
    return k + c;
}

srgb() [1/2]

Color srgb	(	const Color &	color,
		const float	g = float(2.2)
	)

transformation couleur : rgb lineaire vers srgb

Definition at line 61 of file color.cpp.

{
    return Color(srgb(color.r), srgb(color.g), srgb(color.b), color.a);
    
}

linear() [1/2]

Color linear	(	const Color &	color,
		const float	g = float(2.2)
	)

transformation couleur : srgb vers rgb lineaire

Definition at line 67 of file color.cpp.

{
    return Color(linear(color.r), linear(color.g), linear(color.b), color.a);
}

abs()

Color abs

(

const Color &

color

)

Definition at line 129 of file color.cpp.

{
    return Color( std::abs(color.r), std::abs(color.g), std::abs(color.b), std::abs(color.a) ); 
}

read_image()

Image read_image	(	const char *	filename,
		const bool	flipY = true
	)

charge une image .bmp .tga .jpeg .png ou .hdr

Definition at line 94 of file image_io.cpp.

{
    stbi_ldr_to_hdr_scale(1.0f);
    stbi_ldr_to_hdr_gamma(2.2f);
    stbi_set_flip_vertically_on_load(flipY);
    
    int width, height, channels;
    float *data= stbi_loadf(filename, &width, &height, &channels, 4);
    if(!data)
    {
        printf("[error] loading '%s'...\n", filename);
        return {};
    }
    
    Image image(width, height);
    for(unsigned i= 0, offset= 0; i < image.size(); i++, offset+= 4)
        image(i)= Color( data[offset], data[offset + 1], data[offset + 2], data[offset + 3]);
    
    stbi_image_free(data);
    return image;
}

write_image()

bool write_image	(	const Image &	image,
		const char *	filename,
		const bool	flipY = true
	)

enregistre une image au format .png

Definition at line 143 of file image_io.cpp.

{
    return write_image_png(image, filename, flipY );
}

write_image_png()

bool write_image_png	(	const Image &	image,
		const char *	filename,
		const bool	flipY = true
	)

enregistre une image au format .png

Definition at line 124 of file image_io.cpp.

{
    if(image.size() == 0)
        return false;
    
    std::vector<unsigned char> tmp(image.width()*image.height()*4);
    for(unsigned i= 0, offset= 0; i < image.size(); i++, offset+= 4)
    {
        Color pixel= image(i) * 255;
        tmp[offset   ]= clamp(pixel.r, 0, 255);
        tmp[offset +1]= clamp(pixel.g, 0, 255);
        tmp[offset +2]= clamp(pixel.b, 0, 255);
        tmp[offset +3]= clamp(pixel.a, 0, 255);
    }
    
    stbi_flip_vertically_on_write(flipY);
    return stbi_write_png(filename, image.width(), image.height(), 4, tmp.data(), image.width() * 4) != 0;
}

write_image_bmp()

bool write_image_bmp	(	const Image &	image,
		const char *	filename,
		const bool	flipY = true
	)

enregistre une image au format .bmp

Definition at line 148 of file image_io.cpp.

{
    if(image.size() == 0)
        return false;
    
    std::vector<unsigned char> tmp(image.width()*image.height()*4);
    for(unsigned i= 0, offset= 0; i < image.size(); i++, offset+= 4)
    {
        Color pixel= image(i) * 255;
        tmp[offset   ]= clamp(pixel.r, 0, 255);
        tmp[offset +1]= clamp(pixel.g, 0, 255);
        tmp[offset +2]= clamp(pixel.b, 0, 255);
        tmp[offset +3]= clamp(pixel.a, 0, 255);
    }
    
    stbi_flip_vertically_on_write(flipY);
    return stbi_write_bmp(filename, image.width(), image.height(), 4, tmp.data()) != 0;
}

write_image_hdr()

bool write_image_hdr	(	const Image &	image,
		const char *	filename,
		const bool	flipY = true
	)

enregistre une image au format .hdr

Definition at line 167 of file image_io.cpp.

{
    if(image.size() == 0)
        return false;
    
    stbi_flip_vertically_on_write(flipY);
    return stbi_write_hdr(filename, image.width(), image.height(), 4, image.data()) != 0;
}

write_image_preview()

bool write_image_preview	(	const Image &	image,
		const char *	filename,
		const bool	flipY = true
	)

raccourci pour write_image_png(tone(image, range(image)), "image.png")

Definition at line 176 of file image_io.cpp.

{
    if(image.size() == 0)
        return false;
    
    Image tmp= tone(image, range(image));
    return write_image_png(tmp, filename, flipY);
}

srgb() [2/2]

Image srgb

(

const Image &

image

)

transformation couleur : rgb lineaire vers srgb

Definition at line 14 of file image_io.cpp.

{
    Image tmp(image.width(), image.height());
    
    for(unsigned i= 0; i < image.size(); i++)
        tmp(i)= srgb(image(i));
    
    return tmp;
}

linear() [2/2]

Image linear

(

const Image &

image

)

transformation couleur : srgb vers rgb lineaire

Definition at line 24 of file image_io.cpp.

{
    Image tmp(image.width(), image.height());
    
    for(unsigned i= 0; i < image.size(); i++)
        tmp(i)= linear(image(i));
    
    return tmp;
}

range()

float range

(

const Image &

image

)

evalue l'exposition d'une image.

Definition at line 34 of file image_io.cpp.

{
    float gmin= FLT_MAX;
    float gmax= 0;
    for(unsigned i= 0; i < image.size(); i++)
    {
        Color color= image(i);
        float g= color.r + color.g + color.b;
        
        if(g < gmin) gmin= g;
        if(g > gmax) gmax= g;
    }
    
    int bins[100] = {};
    for(unsigned i= 0; i < image.size(); i++)
   {
        Color color= image(i);
        float g= color.r + color.g + color.b;
        
        int b= (g - gmin) * 100 / (gmax - gmin);
        if(b >= 99) b= 99;
        if(b < 0) b= 0;
        bins[b]++;
    }
    
    float saturation= 0;
    float qbins= 0;
    for(unsigned i= 0; i < 100; i++)
    {
        qbins= qbins + float(bins[i]) / float(image.size());
        if(qbins > .75f)
            return gmin + float(i+1) / 100 * (gmax - gmin);
    }
    
    return gmax;
}

tone()

Image tone	(	const Image &	image,
		const float	saturation
	)

correction de l'exposition d'une image + transformation gamma.

Definition at line 72 of file image_io.cpp.

{
    Image tmp(image.width(), image.height());
    
    float k= 1 / std::pow(saturation, 1 / 2.2f);
    for(unsigned i= 0; i < image.size(); i++)
    {
        Color color= image(i);
        if(std::isnan(color.r) || std::isnan(color.g) || std::isnan(color.b))
            // marque les pixels pourris avec une couleur improbable...            
            color= Color(1, 0, 1);
        else
            // sinon transformation rgb -> srgb
            color= k * srgb(color);
        
        tmp(i)= Color(color, 1);
    }
    
    return tmp;
}