如Size
,Width
和Height
是Get()
的性质System.Drawing.Image
;
如何在运行时使用C#调整Image对象的大小?
现在,我正在Image
使用以下方法创建一个新的:
// objImage is the original Image
Bitmap objBitmap = new Bitmap(objImage, new Size(227, 171));
如Size
,Width
和Height
是Get()
的性质System.Drawing.Image
;
如何在运行时使用C#调整Image对象的大小?
现在,我正在Image
使用以下方法创建一个新的:
// objImage is the original Image
Bitmap objBitmap = new Bitmap(objImage, new Size(227, 171));
Answers:
这将执行高质量的调整大小:
/// <summary>
/// Resize the image to the specified width and height.
/// </summary>
/// <param name="image">The image to resize.</param>
/// <param name="width">The width to resize to.</param>
/// <param name="height">The height to resize to.</param>
/// <returns>The resized image.</returns>
public static Bitmap ResizeImage(Image image, int width, int height)
{
var destRect = new Rectangle(0, 0, width, height);
var destImage = new Bitmap(width, height);
destImage.SetResolution(image.HorizontalResolution, image.VerticalResolution);
using (var graphics = Graphics.FromImage(destImage))
{
graphics.CompositingMode = CompositingMode.SourceCopy;
graphics.CompositingQuality = CompositingQuality.HighQuality;
graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
graphics.SmoothingMode = SmoothingMode.HighQuality;
graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;
using (var wrapMode = new ImageAttributes())
{
wrapMode.SetWrapMode(WrapMode.TileFlipXY);
graphics.DrawImage(image, destRect, 0, 0, image.Width,image.Height, GraphicsUnit.Pixel, wrapMode);
}
}
return destImage;
}
wrapMode.SetWrapMode(WrapMode.TileFlipXY)
防止在图像边界周围出现鬼影-幼稚的调整大小将对超出图像边界的透明像素进行采样,但是通过镜像图像,我们可以获得更好的采样(此设置非常明显)destImage.SetResolution
不论物理尺寸如何均保持DPI-缩小图像尺寸或打印时可能会提高质量graphics.CompositingMode
确定源图像中的像素是覆盖还是与背景像素组合。SourceCopy
指定当渲染颜色时,它将覆盖背景颜色。graphics.CompositingQuality
确定分层图像的渲染质量级别。graphics.InterpolationMode
确定如何计算两个端点之间的中间值graphics.SmoothingMode
指定线条,曲线和填充区域的边缘是否使用平滑(也称为抗锯齿)-可能仅适用于矢量graphics.PixelOffsetMode
在绘制新图像时影响渲染质量保持宽高比是读者的一项练习(实际上,我只是认为为您做到这一点不是此功能的工作)。
另外,这是一篇很好的文章,描述了图像大小调整的一些陷阱。上面的功能将覆盖其中的大多数功能,但是您仍然需要担心保存。
Bitmap
本质上只是类的名称,您可以将其保存为所需的任何文件类型。
System.Drawing
并添加using System.Drawing.Imaging;
不确定这样做有什么困难,请执行您的工作,使用重载的Bitmap构造函数创建一个重新调整大小的图像,您唯一缺少的就是将其强制转换为Image数据类型:
public static Image resizeImage(Image imgToResize, Size size)
{
return (Image)(new Bitmap(imgToResize, size));
}
yourImage = resizeImage(yourImage, new Size(50,50));
yourImage
在将其分配给新图像之前进行处理?
在这个问题中,您将得到一些答案,包括我的:
public Image resizeImage(int newWidth, int newHeight, string stPhotoPath)
{
Image imgPhoto = Image.FromFile(stPhotoPath);
int sourceWidth = imgPhoto.Width;
int sourceHeight = imgPhoto.Height;
//Consider vertical pics
if (sourceWidth < sourceHeight)
{
int buff = newWidth;
newWidth = newHeight;
newHeight = buff;
}
int sourceX = 0, sourceY = 0, destX = 0, destY = 0;
float nPercent = 0, nPercentW = 0, nPercentH = 0;
nPercentW = ((float)newWidth / (float)sourceWidth);
nPercentH = ((float)newHeight / (float)sourceHeight);
if (nPercentH < nPercentW)
{
nPercent = nPercentH;
destX = System.Convert.ToInt16((newWidth -
(sourceWidth * nPercent)) / 2);
}
else
{
nPercent = nPercentW;
destY = System.Convert.ToInt16((newHeight -
(sourceHeight * nPercent)) / 2);
}
int destWidth = (int)(sourceWidth * nPercent);
int destHeight = (int)(sourceHeight * nPercent);
Bitmap bmPhoto = new Bitmap(newWidth, newHeight,
PixelFormat.Format24bppRgb);
bmPhoto.SetResolution(imgPhoto.HorizontalResolution,
imgPhoto.VerticalResolution);
Graphics grPhoto = Graphics.FromImage(bmPhoto);
grPhoto.Clear(Color.Black);
grPhoto.InterpolationMode =
System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
grPhoto.DrawImage(imgPhoto,
new Rectangle(destX, destY, destWidth, destHeight),
new Rectangle(sourceX, sourceY, sourceWidth, sourceHeight),
GraphicsUnit.Pixel);
grPhoto.Dispose();
imgPhoto.Dispose();
return bmPhoto;
}
为什么不使用该System.Drawing.Image.GetThumbnailImage
方法?
public Image GetThumbnailImage(
int thumbWidth,
int thumbHeight,
Image.GetThumbnailImageAbort callback,
IntPtr callbackData)
例:
Image originalImage = System.Drawing.Image.FromStream(inputStream, true, true);
Image resizedImage = originalImage.GetThumbnailImage(newWidth, (newWidth * originalImage.Height) / originalWidth, null, IntPtr.Zero);
resizedImage.Save(imagePath, ImageFormat.Png);
来源:http: //msdn.microsoft.com/en-us/library/system.drawing.image.getthumbnailimage.aspx
你可以试试净贵宾,在C#绑定libvips。它是一个惰性的,流式,按需驱动的图像处理库,因此它可以执行此类操作,而无需加载整个图像。
例如,它带有一个方便的图像缩略图:
Image image = Image.Thumbnail("image.jpg", 300, 300);
image.WriteToFile("my-thumbnail.jpg");
它还支持智能裁切,这是一种智能地确定图像最重要部分并在裁切图像时使其聚焦的方法。例如:
Image image = Image.Thumbnail("owl.jpg", 128, crop: "attention");
image.WriteToFile("tn_owl.jpg");
owl.jpg
偏心成分在哪里:
给出以下结果:
首先,它会缩小图像以使垂直轴达到128像素,然后使用该attention
策略将其裁剪为128像素。该图片会在图像中搜索可能引起人眼注意的功能,请参阅Smartcrop()
有关详细信息。
这将 -
//////////////
private void ResizeImage(Image img, double maxWidth, double maxHeight)
{
double resizeWidth = img.Source.Width;
double resizeHeight = img.Source.Height;
double aspect = resizeWidth / resizeHeight;
if (resizeWidth > maxWidth)
{
resizeWidth = maxWidth;
resizeHeight = resizeWidth / aspect;
}
if (resizeHeight > maxHeight)
{
aspect = resizeWidth / resizeHeight;
resizeHeight = maxHeight;
resizeWidth = resizeHeight * aspect;
}
img.Width = resizeWidth;
img.Height = resizeHeight;
}
public static Image resizeImage(Image image, int new_height, int new_width)
{
Bitmap new_image = new Bitmap(new_width, new_height);
Graphics g = Graphics.FromImage((Image)new_image );
g.InterpolationMode = InterpolationMode.High;
g.DrawImage(image, 0, 0, new_width, new_height);
return new_image;
}
这段代码与以上答案之一发布的代码相同。但是会将透明像素转换为白色而不是黑色...谢谢:)
public Image resizeImage(int newWidth, int newHeight, string stPhotoPath)
{
Image imgPhoto = Image.FromFile(stPhotoPath);
int sourceWidth = imgPhoto.Width;
int sourceHeight = imgPhoto.Height;
//Consider vertical pics
if (sourceWidth < sourceHeight)
{
int buff = newWidth;
newWidth = newHeight;
newHeight = buff;
}
int sourceX = 0, sourceY = 0, destX = 0, destY = 0;
float nPercent = 0, nPercentW = 0, nPercentH = 0;
nPercentW = ((float)newWidth / (float)sourceWidth);
nPercentH = ((float)newHeight / (float)sourceHeight);
if (nPercentH < nPercentW)
{
nPercent = nPercentH;
destX = System.Convert.ToInt16((newWidth -
(sourceWidth * nPercent)) / 2);
}
else
{
nPercent = nPercentW;
destY = System.Convert.ToInt16((newHeight -
(sourceHeight * nPercent)) / 2);
}
int destWidth = (int)(sourceWidth * nPercent);
int destHeight = (int)(sourceHeight * nPercent);
Bitmap bmPhoto = new Bitmap(newWidth, newHeight,
PixelFormat.Format24bppRgb);
bmPhoto.SetResolution(imgPhoto.HorizontalResolution,
imgPhoto.VerticalResolution);
Graphics grPhoto = Graphics.FromImage(bmPhoto);
grPhoto.Clear(Color.White);
grPhoto.InterpolationMode =
System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
grPhoto.DrawImage(imgPhoto,
new Rectangle(destX, destY, destWidth, destHeight),
new Rectangle(sourceX, sourceY, sourceWidth, sourceHeight),
GraphicsUnit.Pixel);
grPhoto.Dispose();
imgPhoto.Dispose();
return bmPhoto;
}
在该应用程序中,我创建了一个具有多个选项的函数。它很大,但是可以调整图像的大小,可以保持宽高比,可以切割边缘以仅返回图像的中心:
/// <summary>
/// Resize image with a directory as source
/// </summary>
/// <param name="OriginalFileLocation">Image location</param>
/// <param name="heigth">new height</param>
/// <param name="width">new width</param>
/// <param name="keepAspectRatio">keep the aspect ratio</param>
/// <param name="getCenter">return the center bit of the image</param>
/// <returns>image with new dimentions</returns>
public Image resizeImageFromFile(String OriginalFileLocation, int heigth, int width, Boolean keepAspectRatio, Boolean getCenter)
{
int newheigth = heigth;
System.Drawing.Image FullsizeImage = System.Drawing.Image.FromFile(OriginalFileLocation);
// Prevent using images internal thumbnail
FullsizeImage.RotateFlip(System.Drawing.RotateFlipType.Rotate180FlipNone);
FullsizeImage.RotateFlip(System.Drawing.RotateFlipType.Rotate180FlipNone);
if (keepAspectRatio || getCenter)
{
int bmpY = 0;
double resize = (double)FullsizeImage.Width / (double)width;//get the resize vector
if (getCenter)
{
bmpY = (int)((FullsizeImage.Height - (heigth * resize)) / 2);// gives the Y value of the part that will be cut off, to show only the part in the center
Rectangle section = new Rectangle(new Point(0, bmpY), new Size(FullsizeImage.Width, (int)(heigth * resize)));// create the section to cut of the original image
//System.Console.WriteLine("the section that will be cut off: " + section.Size.ToString() + " the Y value is minimized by: " + bmpY);
Bitmap orImg = new Bitmap((Bitmap)FullsizeImage);//for the correct effect convert image to bitmap.
FullsizeImage.Dispose();//clear the original image
using (Bitmap tempImg = new Bitmap(section.Width, section.Height))
{
Graphics cutImg = Graphics.FromImage(tempImg);// set the file to save the new image to.
cutImg.DrawImage(orImg, 0, 0, section, GraphicsUnit.Pixel);// cut the image and save it to tempImg
FullsizeImage = tempImg;//save the tempImg as FullsizeImage for resizing later
orImg.Dispose();
cutImg.Dispose();
return FullsizeImage.GetThumbnailImage(width, heigth, null, IntPtr.Zero);
}
}
else newheigth = (int)(FullsizeImage.Height / resize);// set the new heigth of the current image
}//return the image resized to the given heigth and width
return FullsizeImage.GetThumbnailImage(width, newheigth, null, IntPtr.Zero);
}
为了使访问该函数更容易,可以添加一些重载的函数:
/// <summary>
/// Resize image with a directory as source
/// </summary>
/// <param name="OriginalFileLocation">Image location</param>
/// <param name="heigth">new height</param>
/// <param name="width">new width</param>
/// <returns>image with new dimentions</returns>
public Image resizeImageFromFile(String OriginalFileLocation, int heigth, int width)
{
return resizeImageFromFile(OriginalFileLocation, heigth, width, false, false);
}
/// <summary>
/// Resize image with a directory as source
/// </summary>
/// <param name="OriginalFileLocation">Image location</param>
/// <param name="heigth">new height</param>
/// <param name="width">new width</param>
/// <param name="keepAspectRatio">keep the aspect ratio</param>
/// <returns>image with new dimentions</returns>
public Image resizeImageFromFile(String OriginalFileLocation, int heigth, int width, Boolean keepAspectRatio)
{
return resizeImageFromFile(OriginalFileLocation, heigth, width, keepAspectRatio, false);
}
现在是最后两个可选的布尔值。像这样调用函数:
System.Drawing.Image ResizedImage = resizeImageFromFile(imageLocation, 800, 400, true, true);
public string CreateThumbnail(int maxWidth, int maxHeight, string path)
{
var image = System.Drawing.Image.FromFile(path);
var ratioX = (double)maxWidth / image.Width;
var ratioY = (double)maxHeight / image.Height;
var ratio = Math.Min(ratioX, ratioY);
var newWidth = (int)(image.Width * ratio);
var newHeight = (int)(image.Height * ratio);
var newImage = new Bitmap(newWidth, newHeight);
Graphics thumbGraph = Graphics.FromImage(newImage);
thumbGraph.CompositingQuality = CompositingQuality.HighQuality;
thumbGraph.SmoothingMode = SmoothingMode.HighQuality;
//thumbGraph.InterpolationMode = InterpolationMode.HighQualityBicubic;
thumbGraph.DrawImage(image, 0, 0, newWidth, newHeight);
image.Dispose();
string fileRelativePath = "newsizeimages/" + maxWidth + Path.GetFileName(path);
newImage.Save(Server.MapPath(fileRelativePath), newImage.RawFormat);
return fileRelativePath;
}
单击此处http://bhupendrasinghsaini.blogspot.in/2014/07/resize-image-in-c.html
这是我为特定要求制定的代码,即:目的地始终为横向比例。它应该给您一个好的开始。
public Image ResizeImage(Image source, RectangleF destinationBounds)
{
RectangleF sourceBounds = new RectangleF(0.0f,0.0f,(float)source.Width, (float)source.Height);
RectangleF scaleBounds = new RectangleF();
Image destinationImage = new Bitmap((int)destinationBounds.Width, (int)destinationBounds.Height);
Graphics graph = Graphics.FromImage(destinationImage);
graph.InterpolationMode =
System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
// Fill with background color
graph.FillRectangle(new SolidBrush(System.Drawing.Color.White), destinationBounds);
float resizeRatio, sourceRatio;
float scaleWidth, scaleHeight;
sourceRatio = (float)source.Width / (float)source.Height;
if (sourceRatio >= 1.0f)
{
//landscape
resizeRatio = destinationBounds.Width / sourceBounds.Width;
scaleWidth = destinationBounds.Width;
scaleHeight = sourceBounds.Height * resizeRatio;
float trimValue = destinationBounds.Height - scaleHeight;
graph.DrawImage(source, 0, (trimValue / 2), destinationBounds.Width, scaleHeight);
}
else
{
//portrait
resizeRatio = destinationBounds.Height/sourceBounds.Height;
scaleWidth = sourceBounds.Width * resizeRatio;
scaleHeight = destinationBounds.Height;
float trimValue = destinationBounds.Width - scaleWidth;
graph.DrawImage(source, (trimValue / 2), 0, scaleWidth, destinationBounds.Height);
}
return destinationImage;
}
如果您正在使用BitmapSource
:
var resizedBitmap = new TransformedBitmap(
bitmapSource,
new ScaleTransform(scaleX, scaleY));
如果要更好地控制质量,请首先运行以下命令:
RenderOptions.SetBitmapScalingMode(
bitmapSource,
BitmapScalingMode.HighQuality);
(默认BitmapScalingMode.Linear
等于BitmapScalingMode.LowQuality
。)
我之所以使用ImageProcessorCore,主要是因为它可以运行.Net Core。
它具有更多选项,例如转换类型,裁剪图像等
调整大小并保存图像以适合宽度和高度,例如画布,使图像保持比例
using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
namespace Infra.Files
{
public static class GenerateThumb
{
/// <summary>
/// Resize and save an image to fit under width and height like a canvas keeping things proportional
/// </summary>
/// <param name="originalImagePath"></param>
/// <param name="thumbImagePath"></param>
/// <param name="newWidth"></param>
/// <param name="newHeight"></param>
public static void GenerateThumbImage(string originalImagePath, string thumbImagePath, int newWidth, int newHeight)
{
Bitmap srcBmp = new Bitmap(originalImagePath);
float ratio = 1;
float minSize = Math.Min(newHeight, newHeight);
if (srcBmp.Width > srcBmp.Height)
{
ratio = minSize / (float)srcBmp.Width;
}
else
{
ratio = minSize / (float)srcBmp.Height;
}
SizeF newSize = new SizeF(srcBmp.Width * ratio, srcBmp.Height * ratio);
Bitmap target = new Bitmap((int)newSize.Width, (int)newSize.Height);
using (Graphics graphics = Graphics.FromImage(target))
{
graphics.CompositingQuality = CompositingQuality.HighSpeed;
graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
graphics.CompositingMode = CompositingMode.SourceCopy;
graphics.DrawImage(srcBmp, 0, 0, newSize.Width, newSize.Height);
using (MemoryStream memoryStream = new MemoryStream())
{
target.Save(thumbImagePath);
}
}
}
}
}
将以下功能与以下示例结合使用以更改图像尺寸:
//Example :
System.Net.Mime.MediaTypeNames.Image newImage = System.Net.Mime.MediaTypeNames.Image.FromFile("SampImag.jpg");
System.Net.Mime.MediaTypeNames.Image temImag = FormatImage(newImage, 100, 100);
//image size modification unction
public static System.Net.Mime.MediaTypeNames.Image FormatImage(System.Net.Mime.MediaTypeNames.Image img, int outputWidth, int outputHeight)
{
Bitmap outputImage = null;
Graphics graphics = null;
try
{
outputImage = new Bitmap(outputWidth, outputHeight, System.Drawing.Imaging.PixelFormat.Format16bppRgb555);
graphics = Graphics.FromImage(outputImage);
graphics.DrawImage(img, new Rectangle(0, 0, outputWidth, outputHeight),
new Rectangle(0, 0, img.Width, img.Height), GraphicsUnit.Pixel);
return outputImage;
}
catch (Exception ex)
{
return img;
}
}
您可以为此使用Accord.NET框架。它提供了几种不同的大小调整方法:
注意:这不适用于ASP.Net Core,因为WebImage依赖于System.Web,但是在ASP.Net的早期版本中,我多次使用了此代码段,这很有用。
String ThumbfullPath = Path.GetFileNameWithoutExtension(file.FileName) + "80x80.jpg";
var ThumbfullPath2 = Path.Combine(ThumbfullPath, fileThumb);
using (MemoryStream stream = new MemoryStream(System.IO.File.ReadAllBytes(fullPath)))
{
var thumbnail = new WebImage(stream).Resize(80, 80);
thumbnail.Save(ThumbfullPath2, "jpg");
}