开源项目学习(1) ---- FreeImage 使用指南

女爷i 2024-03-17 15:45 57阅读 0赞

### **1. FreeImage 简介** ###

FreeImage 官网：

> [The FreeImage Project][]

FreeImage 的英文版功能简介如下：

*  Loading and Saving of as many bitmap types as possible
 *  Easy access to bitmap components,such as palette and data bits
 *  Converting bitmap’s bit depths from one to another
 *  Accessing pages in a bitmap when there are multiple.such as in TIFF
 *  basic manipulation of bitmaps,such as roation,flipping and resampling or point
 *  Alpha compositing and alpha blending

FreeImage 支持几乎所有图片格式的解析，解码，转码，图像处理，支持的图片格式包括 PNG，JPG，BMP，TGA，TIFF ... ；支持的图像处理操作包括 gamma校正，对比度，亮度，toneMapping，Alpha blending 等

FreeImage doesnot support:

*  Advanced image processing operations such as convolution and transforms
 *  Bitmap drawing
 *  Vector graphics

### **2.FreeImage 使用方法** ###

FreeImage 支持 VisualStudio，Linux，Cygwin，MacoS 等平台，在 windows下开发可以直接下载编译好的 动态链接库文件，在VisualStudio 中设置对应的头文件和库文件的路径

![357a3d2aecbd49659302d49eaf2bd957.png][]

x32 和 x64 平台的库都有提供，注意设置时要对对应平台设置头文件和库文件路径。

Visual Studio 中设置方法请参考下面的博客：

> [图形图像处理算法（1）---- VisualStudio OpenCV 验证平台搭建 - 简书][1_---- VisualStudio OpenCV _ -]

FreeImage 详细的参考文档餐卡官网的文档 [Download FreeImage3180.pdf][]

### **3.FreeImage API 简介** ###

#### **3.1 初始化API** ####

DLL_API void DLL_CALLCONV FreeImage_Initialise(BOOL load_local_plugins_only FI_DEFAULT(FALSE));
    DLL_API void DLL_CALLCONV FreeImage_DeInitialise(void);
    
    // Version routines ---------------------------------------------------------
    
    DLL_API const char *DLL_CALLCONV FreeImage_GetVersion(void);
    DLL_API const char *DLL_CALLCONV FreeImage_GetCopyrightMessage(void);

#### **3.2 图像加载，保存相关API** ####

FreeImage 不仅支持从文件中加载，可以直接从 File\* 类型的handle 中加载图像

DLL_API FIBITMAP *DLL_CALLCONV FreeImage_Allocate(int width, int height, int bpp, unsigned red_mask FI_DEFAULT(0), unsigned green_mask FI_DEFAULT(0), unsigned blue_mask FI_DEFAULT(0));
    DLL_API FIBITMAP *DLL_CALLCONV FreeImage_AllocateT(FREE_IMAGE_TYPE type, int width, int height, int bpp FI_DEFAULT(8), unsigned red_mask FI_DEFAULT(0), unsigned green_mask FI_DEFAULT(0), unsigned blue_mask FI_DEFAULT(0));
    DLL_API FIBITMAP * DLL_CALLCONV FreeImage_Clone(FIBITMAP *dib);
    DLL_API void DLL_CALLCONV FreeImage_Unload(FIBITMAP *dib);
    DLL_API FIBITMAP *DLL_CALLCONV FreeImage_Load(FREE_IMAGE_FORMAT fif, const char *filename, int flags FI_DEFAULT(0));
    DLL_API FIBITMAP *DLL_CALLCONV FreeImage_LoadU(FREE_IMAGE_FORMAT fif, const wchar_t *filename, int flags FI_DEFAULT(0));
    DLL_API FIBITMAP *DLL_CALLCONV FreeImage_LoadFromHandle(FREE_IMAGE_FORMAT fif, FreeImageIO *io, fi_handle handle, int flags FI_DEFAULT(0));
    DLL_API BOOL DLL_CALLCONV FreeImage_Save(FREE_IMAGE_FORMAT fif, FIBITMAP *dib, const char *filename, int flags FI_DEFAULT(0));

#### **3.3 获取图像信息相关API** ####

**FreeImage 提供了丰富的 API 获取图像的所有信息**

void testFreeImagebitmapinfo(int argc, char **argv) {
    	FreeImage_Initialise(FALSE);
    	FIBITMAP *allocatelib = NULL;
    
    	allocatelib = FreeImage_Load(FIF_JPEG, "freeimage.jpg", JPEG_DEFAULT);
    
    	printf("FreeImage get image type: %d \n", FreeImage_GetImageType(allocatelib));
    
    	printf("FreeImage get color used: %d \n", FreeImage_GetColorsUsed(allocatelib));
    
    	printf("FreeImage get BPP : %d \n", FreeImage_GetBPP(allocatelib));
    
    	printf("FreeImage get Width : %d \n", FreeImage_GetWidth(allocatelib));
    	printf("FreeImage get Height : %d \n", FreeImage_GetHeight(allocatelib));
    
    	printf("FreeImage get Line : %d \n", FreeImage_GetLine(allocatelib));
    	printf("FreeImage get Pitch : %d \n", FreeImage_GetPitch(allocatelib));
    
    	printf("FreeImage get DIBSize : %d \n", FreeImage_GetDIBSize(allocatelib));
    	printf("FreeImage get MemorySize : %d \n", FreeImage_GetMemorySize(allocatelib));
    	RGBQUAD *palette = NULL;
        printf("FreeImage get Palette : %d \n", (((palette = FreeImage_GetPalette(allocatelib)) == NULL)? TRUE : FALSE));
    
    	// dpx
    	printf("FreeImage get GetDotsPerMeterX : %d \n", FreeImage_GetDotsPerMeterX(allocatelib));
    	// dpy
    	printf("FreeImage get GetDotsPerMeterY : %d \n", FreeImage_GetDotsPerMeterY(allocatelib));
    
    	FreeImage_SetDotsPerMeterX(allocatelib, 1000);
    	FreeImage_SetDotsPerMeterY(allocatelib, 1000);
    
    	CHECKBOOL(FreeImage_Save(FIF_PNG, allocatelib, "freeimage.png", PNG_DEFAULT));
    
    
    	BITMAPINFOHEADER *bitmapHeader = FreeImage_GetInfoHeader(allocatelib);
    	if (bitmapHeader) {
    		printf("FreeImage GetInfoHeader success!! \n");
    	}
    
    	BITMAPINFO *bitmapInfo = FreeImage_GetInfo(allocatelib);
    	if (bitmapHeader) {
    		printf("FreeImage GetInfoHeader success!! \n");
    	}
    	//  2 FIC_RGB
    	printf("FreeImage get colortype:%d \n", FreeImage_GetColorType(allocatelib));
    
    	//  RedMask:ff0000 GreenMask:ff00 BlueMask:ff
    	printf("FreeImage get RedMask:%x GreenMask:%x BlueMask:%x \n", FreeImage_GetRedMask(allocatelib), \
    		FreeImage_GetGreenMask(allocatelib), FreeImage_GetBlueMask(allocatelib));
    
    	printf("FreeImage Has Pixels %d \n", FreeImage_HasPixels(allocatelib));
    
    
    	FIBITMAP *thumbnail = FreeImage_GetThumbnail(allocatelib);
    	if (!thumbnail) {
    		printf("get thumbnail failed!! \n");
    	}

#### **3.4 获取像素地址API** ####

通过 **FreeImage\_GetBits** 和 **FreeImage\_GetScanLine** 可以获取图像首地址和每一行的内存地址，为编辑每一个像素的内容提供了可能，结合自己的绘制代码，间接实现绘制图像的功能。

void testFreeImagePixelAccess(int argc, char **argv) {
    	FreeImage_Initialise(FALSE);
    	FIBITMAP *allocatelib = NULL;
    	allocatelib = FreeImage_Allocate(1280, 720, 32);
    	CHECKNULL(allocatelib);
    
    	BYTE* ptr = FreeImage_GetBits(allocatelib);
    	
    	printf("FreeImage get BPP : %d \n", FreeImage_GetBPP(allocatelib));
    	printf("FreeImage get Width : %d \n", FreeImage_GetWidth(allocatelib));
    	printf("FreeImage get Height : %d \n", FreeImage_GetHeight(allocatelib));
    
    	for(unsigned int y = 0; y < FreeImage_GetHeight(allocatelib); y++) {
    		BYTE* ptr = FreeImage_GetScanLine(allocatelib, y);
    		for (unsigned int x = 0; x < FreeImage_GetWidth(allocatelib); x++) {
    			ptr[FI_RGBA_RED] = 0;
    			ptr[FI_RGBA_GREEN] = 255;
    			ptr[FI_RGBA_BLUE] = 0;
    			ptr[FI_RGBA_ALPHA] = 255;
    			ptr += FreeImage_GetBPP(allocatelib)/8;
    		}
    	}
    
    	RGBQUAD pixelColor;
    	FreeImage_GetPixelColor(allocatelib, 100, 100, &pixelColor);
    	printf("FreeImage get Pixel color: R:%d G:%d B:%d \n", pixelColor.rgbRed, pixelColor.rgbGreen, pixelColor.rgbBlue);
    
    	int start_x = 100;
    	int start_y = 100;
    	int rect_w = 200;
    	int rect_h = 200;
    
    	pixelColor.rgbRed = 255;
    	pixelColor.rgbGreen = 0;
    	pixelColor.rgbBlue = 0;
    
    	for (int y = start_y; y < (rect_h + start_y); y++) {
    		for (int x = start_x; x < (rect_w + start_x); x++) {
    			FreeImage_SetPixelColor(allocatelib, x, y, &pixelColor);
    		}
    	}
    
    	CHECKBOOL(FreeImage_Save(FIF_BMP, allocatelib, "allocate.bmp", BMP_DEFAULT));
    
    EXIT:
    	if (allocatelib) {
    		FreeImage_Unload(allocatelib);
    	}
    
    	FreeImage_DeInitialise();
    }

#### **3.5 图像格式转换API**  ####

通过 **FreeImage\_ConvertTo4Bits FreeImage\_ConvertTo8Bits** 可以实现图像在各个不同颜色通道和颜色色深之间转换，注意使用 **FreeImage\_ConvertTo4Bits** 实际是转换为使用 palette 格式的图片，4Bits 对应的是 16 个颜色，图像中存储是是这16种颜色的索引值

void testFreeImageConversion(int argc, char **argv) {
    	FreeImage_Initialise(FALSE);
    	FIBITMAP *allocatelib = NULL;
    	allocatelib = FreeImage_Load(FIF_JPEG, "freeimage.jpg", JPEG_DEFAULT);
    	CHECKNULL(allocatelib);
    
    	// 4 bits and 8 bits using palette
    	//FIBITMAP* outputlib = FreeImage_ConvertTo8Bits(allocatelib);
    	FIBITMAP* outputlib = FreeImage_ConvertTo4Bits(allocatelib);
    	printf("FreeImage get BPP : %d \n", FreeImage_GetBPP(outputlib));
    	printf("FreeImage get Width : %d \n", FreeImage_GetWidth(outputlib));
    	printf("FreeImage get Height : %d \n", FreeImage_GetHeight(outputlib));
    	//printf("FreeImage get Palette : %d \n", FreeImage_GetPalette(allocatelib));
    
    	const BITMAPINFOHEADER *bitmapHeader = FreeImage_GetInfoHeader(outputlib);
    	if (bitmapHeader) {
    		printf("color used %d  color important %d\n", bitmapHeader->biClrUsed, bitmapHeader->biClrImportant);
    
    		const RGBQUAD* palette = FreeImage_GetPalette(outputlib);
    		for (int i = 0; i < (bitmapHeader->biClrUsed); i++) {
    			printf("%d %d %d \n", palette[i].rgbRed, palette[i].rgbGreen, palette[i].rgbBlue);
    		}
    	}
    
    	CHECKBOOL(FreeImage_Save(FIF_BMP, outputlib, "outputlib_4Bits.bmp", BMP_DEFAULT));
    
    EXIT:
    	if (allocatelib) {
    		FreeImage_Unload(allocatelib);
    	}
    
    	FreeImage_DeInitialise();
    }

#### **3.6 图像处理相关API** ####

包含对图像的 旋转，Gamma，对比度调节等处理，使用 FreeImage\_Paste 还可以实现图像的 alpha blend 效果

FreeImage_Initialise(FALSE);
    	FIBITMAP *allocatelib = NULL;
    	FIBITMAP *output_lib = NULL;
    	FIBITMAP *srclib = NULL;
    	allocatelib = FreeImage_Load(FIF_JPEG, "freeimage.jpg", JPEG_DEFAULT);
    	CHECKNULL(allocatelib);
    
    	output_lib = FreeImage_Rotate(allocatelib, 90.0);
    	//CHECKBOOL(FreeImage_Save(FIF_BMP, output_lib, "rotate.bmp", BMP_DEFAULT));
    
    	double x_orig = FreeImage_GetWidth(allocatelib) / 2.0;
    	double y_orig = FreeImage_GetHeight(allocatelib) / 2.0;
    	output_lib = FreeImage_RotateEx(allocatelib, 45.0, 0.0, 0.0, x_orig, y_orig, TRUE);
    	//CHECKBOOL(FreeImage_Save(FIF_BMP, output_lib, "rotate.bmp", BMP_DEFAULT));
    
    	//  alpha blend demo
    	srclib = FreeImage_Load(FIF_JPEG, "tony_logo.jpg", JPEG_DEFAULT);
    
    	FreeImage_Paste(allocatelib, srclib, (int)x_orig, (int)y_orig, 100);
    	CHECKBOOL(FreeImage_Save(FIF_BMP, allocatelib, "blend.bmp", BMP_DEFAULT));

[The FreeImage Project]: https://freeimage.sourceforge.io/
[357a3d2aecbd49659302d49eaf2bd957.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/15/d72d179273d04cef8be3b6ed307ad8f8.png
[1_---- VisualStudio OpenCV _ -]: https://www.jianshu.com/p/f8371741e04b
[Download FreeImage3180.pdf]: http://downloads.sourceforge.net/freeimage/FreeImage3180.pdf