数字图像处理实验报告(三四五).doc
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1、.实验三 图像的几何变换一实验目的及要求掌握图像几何变换的基本原理,熟练掌握数字图像的缩放、旋转、平移、镜像和转置的基本原理及其 MATLAB编程实现方法。二、实验内容(一)研究以下程序,分析程序功能;输入执行各命令行,认真观察命令执行的结果。熟悉程序中所使用函数的调用方法,改变有关参数,观察试验结果。1. 图像缩放clear all, close allI = imread(cameraman.tif);Scale = 1.35; % 将图像放大 1.35倍J1 = imresize(I, Scale, nearest); % using the nearest neighbor inter
2、polationJ2 = imresize(I, Scale, bilinear); % using the bilinear interpolationimshow(I), title(Original Image);figure, imshow(J1), title(Resized Image- using the nearest neighbor interpolation );figure, imshow(J2), title(Resized Image- using the bilinear interpolation );% 查看 imresize使用帮助help imresize
3、Command窗口显示如下:IMRESIZE Resize image.B = IMRESIZE(A, SCALE) returns an image that is SCALE times thesize of A, which is a grayscale, RGB, or binary image.B = IMRESIZE(A, NUMROWS NUMCOLS) resizes the image so that it hasthe specified number of rows and columns. Either NUMROWS or NUMCOLSmay be NaN, in
4、which case IMRESIZE computes the number of rows orcolumns automatically in order to preserve the image aspect ratio.Y, NEWMAP = IMRESIZE(X, MAP, SCALE) resizes an indexed image.Y, NEWMAP = IMRESIZE(X, MAP, NUMROWS NUMCOLS) resizes an indexedimage.To control the interpolation method used by IMRESIZE,
5、 add a METHODargument to any of the syntaxes above, like this:IMRESIZE(A, SCALE, METHOD) IMRESIZE(A, NUMROWS NUMCOLS, METHOD),IMRESIZE(X, MAP, M, METHOD)IMRESIZE(X, MAP, NUMROWS NUMCOLS, METHOD)METHOD can be a string naming a general interpolation method:nearest - nearest-neighbor interpolationbilin
6、ear - bilinear interpolationbicubic - cubic interpolation; the default methodMETHOD can also be a string naming an interpolation kernel:box - interpolation with a box-shaped kerneltriangle - interpolation with a triangular kernel(equivalent to bilinear)cubic - interpolation with a cubic kernel (equi
7、valent to bicubic)lanczos2 - interpolation with a Lanczos-2 kernellanczos3 - interpolation with a Lanczos-3 kernelFinally, METHOD can be a two-element cell array of the form f,w,where f is the function handle for a custom interpolation kernel, andw is the custom kernels width. f(x) must be zero outs
8、ide theinterval -w/2 = x w/2. Your function handle f may be called with ascalar or a vector input.You can achieve additional control over IMRESIZE by usingparameter/value pairs following any of the syntaxes above. Forexample:B = IMRESIZE(A, SCALE, PARAM1, VALUE1, PARAM2, VALUE2, .)Parameters include
9、:.Antialiasing - true or false; specifies whether to perform antialiasing when shrinking an image. Thedefault value depends on the interpolation method you choose. For the nearest method,the default is false; for all other methods,the default is true.Colormap - (only relevant for indexed images) ori
10、ginalor optimized; if original, then theoutput newmap is the same as the input map.If it is optimized, then a new optimizedcolormap is created. The default value isoptimized. Dither - (only for indexed images) true or false;specifies whether to perform colordithering. The default value is true.Metho
11、d - As described aboveOutputSize - A two-element vector, MROWS NCOLS,specifying the output size. One element maybe NaN, in which case the other value iscomputed automatically to preserve the aspectratio of the image. Scale - A scalar or two-element vector specifying theresize scale factors. If it is
12、 a scalar, thesame scale factor is applied to eachdimension. If it is a vector, it containsthe scale factors for the row and columndimensions, respectively.Examples-Shrink by factor of two using the defaults of bicubic interpolationand antialiasing.I = imread(rice.png);J = imresize(I, 0.5);figure, i
13、mshow(I), figure, imshow(J)Shrink by factor of two using nearest-neighbor interpolation.(This is the fastest method, but it has the lowest quality.).J2 = imresize(I, 0.5, nearest);Resize an indexed image.X, map = imread(trees.tif);Y, newmap = imresize(X, map, 0.5);imshow(Y, newmap)Resize an RGB imag
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