调整放置在byte[]数组中的图像的大小
本文关键字:图像 数组 byte 调整 | 更新日期: 2023-09-27 18:19:46
调整放置在byte[]数组中的图像的大小(不知道图像的类型)。我必须生成另一个字节[]数组,其大小应该高达50kB。如何进行某种缩放?
除非你想学习一些严肃的数学,否则你需要将字节数组加载到内存流中,从该内存流加载图像,并使用System.Drawing命名空间中的内置GDI函数。
做25%或50%的量表很容易。除此之外,您还需要开始进行插值和差分,以使二进制数据处理中的任何内容看起来都不太好。在匹配GDI中已有的内容之前,您还需要几天的时间。
System.IO.MemoryStream myMemStream = new System.IO.MemoryStream(myBytes);
System.Drawing.Image fullsizeImage = System.Drawing.Image.FromStream(myMemStream);
System.Drawing.Image newImage = fullsizeImage .GetThumbnailImage(newWidth, newHeight, null, IntPtr.Zero);
System.IO.MemoryStream myResult = new System.IO.MemoryStream();
newImage.Save(myResult ,System.Drawing.Imaging.ImageFormat.Gif); //Or whatever format you want.
return myResult.ToArray(); //Returns a new byte array.
BTW-如果你真的需要弄清楚你的源图像类型,请参阅:如何检查字节数组是否是有效的图像
好的,经过一些实验,我有了这样的东西:
public static byte[] Resize2Max50Kbytes(byte[] byteImageIn)
{
byte[] currentByteImageArray = byteImageIn;
double scale = 1f;
if (!IsValidImage(byteImageIn))
{
return null;
}
MemoryStream inputMemoryStream = new MemoryStream(byteImageIn);
Image fullsizeImage = Image.FromStream(inputMemoryStream);
while (currentByteImageArray.Length > 50000)
{
Bitmap fullSizeBitmap = new Bitmap(fullsizeImage, new Size((int)(fullsizeImage.Width * scale), (int)(fullsizeImage.Height * scale)));
MemoryStream resultStream = new MemoryStream();
fullSizeBitmap.Save(resultStream, fullsizeImage.RawFormat);
currentByteImageArray = resultStream.ToArray();
resultStream.Dispose();
resultStream.Close();
scale -= 0.05f;
}
return currentByteImageArray;
}
有人有其他想法吗?不幸的是,Image.GetThumbnailImage()导致了非常脏的图像。
下面更新的答案适用于Docker SixLabors.ImageSharp
.net核心3.1及更高版本的解决方案:
- 安装
System.Drawing.Common
nuget:
Install-Package System.Drawing.Common
- 更改字节数组中图像大小的代码:
byte[] ReduceImage(byte[] bytes)
{
using var memoryStream = new MemoryStream(bytes);
using var originalImage = new Bitmap(memoryStream);
var resized = new Bitmap(newWidth, newHeight);
using var graphics = Graphics.FromImage(resized);
graphics.CompositingQuality = CompositingQuality.HighSpeed;
graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
graphics.CompositingMode = CompositingMode.SourceCopy;
graphics.DrawImage(originalImage, 0, 0, reducedWidth, reducedHeight);
using var stream = new MemoryStream();
resized.Save(stream, ImageFormat.Png);
return stream.ToArray();
}
更新:上面的方法不适用于Linux,所以通用的解决方案是:
- 安装
SixLabors.ImageSharp
nuget:
Install-Package SixLabors.ImageSharp
- 编写以下代码:
private static byte[] ReduceImage(byte[] bytes)
{
using var memoryStream = new MemoryStream(bytes);
using var image = Image.Load(memoryStream);
image.Mutate(x => x.Resize(ReducedWidth, ReducedHeight));
using var outputStream = new MemoryStream();
image.Save(outputStream, new PngEncoder() /*or another encoder*/);
return outputStream.ToArray();
}
假设您从Drive 读取了一个文件
FileStream streamObj = System.IO.File.OpenRead(@"C:'Files'Photo.jpg");
Byte[] newImage=UploadFoto(streamObj);
public static Byte[] UploadFoto(FileStream fileUpload)
{
Byte[] imgByte = null;
imgByte = lnkUpload(fileUpload);
return imgByte;
}
private static Byte[] lnkUpload(FileStream img)
{
byte[] resizedImage;
using (Image orginalImage = Image.FromStream(img))
{
ImageFormat orginalImageFormat = orginalImage.RawFormat;
int orginalImageWidth = orginalImage.Width;
int orginalImageHeight = orginalImage.Height;
int resizedImageWidth = 60; // Type here the width you want
int resizedImageHeight = Convert.ToInt32(resizedImageWidth * orginalImageHeight / orginalImageWidth);
using (Bitmap bitmapResized = new Bitmap(orginalImage, resizedImageWidth, resizedImageHeight))
{
using (MemoryStream streamResized = new MemoryStream())
{
bitmapResized.Save(streamResized, orginalImageFormat);
resizedImage = streamResized.ToArray();
}
}
}
return resizedImage;
}
我没有明确的实现,但我会这样做:
您可以存储51200个值(未压缩)。你知道原始的比例:用比率和新图像的大小计算尺寸:
x = y / ratio
size(51200) = x * y
y = size / x
x = (size / x) / ratio;
y = x * ratio
对于使用过滤器内核对值进行重新采样:http://en.wikipedia.org/wiki/Lanczos_resampling
还没有用过,但听起来很有希望。
我已经习惯了。。。。
public static byte[] ImagenToByteArray(System.Drawing.Image imageIn)
{
MemoryStream ms = new MemoryStream();
imageIn.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
return ms.ToArray();
}