dlxeon에 의해 게시 한 SO link이 우수합니다. 나는 그곳에서 본보기를 사용한다. 그러나이 모든 예제는 이미지의 크기를 조정하지만 jpeg 파일의 압축률을 높이거나 \를 낮추거나 DPI를 낮출 수도 있습니다.
다음은 jpeg의 크기를 조정하고 압축하는 방법에 대한 전체 예제입니다. 또한 휴대 전화가 수직으로 고정 된 경우 이미지가 회전해야하는지 확인합니다. 이미지를 정사각형으로 만들려면 패딩을 추가 할 수 있습니다.
이 예제를 그대로 사용하면 .png 및 .gif 파일의 투명도가 jpg로 변환되므로 손실됩니다.
protected void SubmitButton_Click(object sender, EventArgs e)
{
if (FileUpload1.HasFile == true)
{
using (Bitmap postedImage = new Bitmap(FileUpload1.PostedFile.InputStream))
{
byte [] bin = Common.scaleImage(postedImage, 400, 400, false);
Image1.ImageUrl = "data:image/jpeg;base64," + Convert.ToBase64String(bin);
}
}
}
public static byte[] scaleImage(Image image, int maxWidth, int maxHeight, bool padImage)
{
try
{
int newWidth;
int newHeight;
byte[] returnArray;
//check if the image needs rotating (eg phone held vertical when taking a picture for example)
foreach (var prop in image.PropertyItems)
{
if (prop.Id == 0x0112)
{
int rotateValue = image.GetPropertyItem(prop.Id).Value[0];
RotateFlipType flipType = getRotateFlipType(rotateValue);
image.RotateFlip(flipType);
break;
}
}
//apply padding if needed
if (padImage == true)
{
image = applyPaddingToImage(image);
}
//check if the with or height of the image exceeds the maximum specified, if so calculate the new dimensions
if (image.Width > maxWidth || image.Height > maxHeight)
{
var ratioX = (double)maxWidth/image.Width;
var ratioY = (double)maxHeight/image.Height;
var ratio = Math.Min(ratioX, ratioY);
newWidth = (int)(image.Width * ratio);
newHeight = (int)(image.Height * ratio);
}
else
{
newWidth = image.Width;
newHeight = image.Height;
}
//start with a new image
var newImage = new Bitmap(newWidth, newHeight);
//set the new resolution, 72 is usually good enough for displaying images on monitors
newImage.SetResolution(72, 72);
//or use the original resolution
//newImage.SetResolution(image.HorizontalResolution, image.VerticalResolution);
//resize the image
using (var graphics = Graphics.FromImage(newImage))
{
graphics.CompositingMode = CompositingMode.SourceCopy;
graphics.CompositingQuality = CompositingQuality.HighQuality;
graphics.SmoothingMode = SmoothingMode.HighQuality;
graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;
graphics.DrawImage(image, 0, 0, newWidth, newHeight);
}
image = newImage;
//save the image to a memorystream to apply the compression level, higher compression = better quality = bigger images
using (MemoryStream ms = new MemoryStream())
{
EncoderParameters encoderParameters = new EncoderParameters(1);
encoderParameters.Param[0] = new EncoderParameter(Encoder.Quality, 80L);
image.Save(ms, getEncoderInfo("image/jpeg"), encoderParameters);
//save the stream as byte array
returnArray = ms.ToArray();
}
//cleanup
image.Dispose();
newImage.Dispose();
return returnArray;
}
catch (Exception ex)
{
//there was an error: ex.Message
return null;
}
}
private static ImageCodecInfo getEncoderInfo(string mimeType)
{
ImageCodecInfo[] encoders = ImageCodecInfo.GetImageEncoders();
for (int j = 0; j < encoders.Length; ++j)
{
if (encoders[j].MimeType.ToLower() == mimeType.ToLower())
return encoders[j];
}
return null;
}
private static Image applyPaddingToImage(Image image)
{
//get the maximum size of the image dimensions
int maxSize = Math.Max(image.Height, image.Width);
Size squareSize = new Size(maxSize, maxSize);
//create a new square image
Bitmap squareImage = new Bitmap(squareSize.Width, squareSize.Height);
using (Graphics graphics = Graphics.FromImage(squareImage))
{
//fill the new square with a color
graphics.FillRectangle(Brushes.Red, 0, 0, squareSize.Width, squareSize.Height);
graphics.CompositingMode = CompositingMode.SourceCopy;
graphics.CompositingQuality = CompositingQuality.HighQuality;
graphics.SmoothingMode = SmoothingMode.HighQuality;
graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;
//put the original image on top of the new square
graphics.DrawImage(image, (squareSize.Width/2) - (image.Width/2), (squareSize.Height/2) - (image.Height/2), image.Width, image.Height);
}
return squareImage;
}
private static RotateFlipType getRotateFlipType(int rotateValue)
{
RotateFlipType flipType = RotateFlipType.RotateNoneFlipNone;
switch (rotateValue)
{
case 1:
flipType = RotateFlipType.RotateNoneFlipNone;
break;
case 2:
flipType = RotateFlipType.RotateNoneFlipX;
break;
case 3:
flipType = RotateFlipType.Rotate180FlipNone;
break;
case 4:
flipType = RotateFlipType.Rotate180FlipX;
break;
case 5:
flipType = RotateFlipType.Rotate90FlipX;
break;
case 6:
flipType = RotateFlipType.Rotate90FlipNone;
break;
case 7:
flipType = RotateFlipType.Rotate270FlipX;
break;
case 8:
flipType = RotateFlipType.Rotate270FlipNone;
break;
default:
flipType = RotateFlipType.RotateNoneFlipNone;
break;
}
return flipType;
}
표시 하시겠습니까? – ChrisBint
여기에 추가하려고합니다. 또한 디스플레이 용 – Orion