We Keep Coding

Using Graphics.DrawImage , changes the background of my transparent PNG images , to black

I've write this method to resize my images, but the returned image for my transparent PNG images, has a black background.
What is the solution?
I've tried Bitmap.MakeTransparent() and also Graphics.Clear() but couldn't solve my problem.
I've checked all related questions, but couldn't find any useful answer to my question.
public HttpResponseMessage ImageResizer(string path, int w,int h)
{
var imagePath = HttpContext.Current.Server.MapPath(path);
Bitmap image;
try
{
image = (Bitmap)System.Drawing.Image.FromFile(imagePath);
}
catch
{
HttpResponseMessage hrm = new HttpResponseMessage();
return hrm;
}
int originalWidth = image.Width;
int originalHeight = image.Height;
// New width and height based on aspect ratio
int newWidth = w;
int newHeight = h;
// Convert other formats (including CMYK) to RGB.
Bitmap newImage = new Bitmap(newWidth, newHeight, PixelFormat.Format24bppRgb);
// Draws the image in the specified size with quality mode set to HighQuality
using (Graphics graphics = Graphics.FromImage(newImage))
{
graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
graphics.SmoothingMode = SmoothingMode.AntiAlias;
graphics.CompositingQuality = CompositingQuality.HighQuality;
graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;
using (var attribute = new ImageAttributes())
{
attribute.SetWrapMode(WrapMode.TileFlipXY);
// draws the resized image to the bitmap
graphics.DrawImage(image, new Rectangle(0, 0, newImage.Width, newImage.Height), new Rectangle(0, 0, originalWidth, originalHeight), GraphicsUnit.Pixel);
}
}
// Get an ImageCodecInfo object that represents the PNG codec.
ImageCodecInfo imageCodecInfo = this.GetEncoderInfo(ImageFormat.Png);
// Create an Encoder object for the Quality parameter.
Encoder encoder = Encoder.Quality;
// Create an EncoderParameters object.
EncoderParameters encoderParameters = new EncoderParameters(1);
// Save the image as a PNG file with quality level.
EncoderParameter encoderParameter = new EncoderParameter(encoder, 10);
encoderParameters.Param[0] = encoderParameter;
var splitPath = imagePath.Split('.');
string newPath = splitPath[0] + "ss5.png";
newImage.Save(newPath, ImageFormat.Png);
MemoryStream memoryStream = new MemoryStream();
newImage.Save(memoryStream, System.Drawing.Imaging.ImageFormat.Png);
HttpResponseMessage response = new HttpResponseMessage();
response.Content = new ByteArrayContent(memoryStream.ToArray());
response.Content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("image/png");
response.Content.Headers.ContentLength = memoryStream.Length;
return response;
}
private ImageCodecInfo GetEncoderInfo(ImageFormat format)
{
return ImageCodecInfo.GetImageDecoders().SingleOrDefault(c => c.FormatID == format.Guid);
}

You are using PixelFormat.Format24bppRgb in your Bitmap constructor. That format is limiting your bitmap to 3 channels: red, green, and blue. Because of this, the bitmap you are creating doesn't support alpha (a.k.a. transparency) and will default to a solid black image. When you draw an image with transparency in it, the alpha of that image will either be pre-multiplied or discarded, depending on its format.
If you want to save your new image with transparency, you need to declare it with PixelFormat.Format32bppArgb:
Bitmap newImage = new Bitmap(newWidth, newHeight, PixelFormat.Format32bppArgb);

Grey and unsharp images when resizing using GDI+

I'm using asp.net mvc 3 to stream resized images. But the output of the image is greyish and blury eventhough I've set smoothingmode and interpolationmode to highbiqubic.
public ActionResult ImageTEST(int fileID, int width, int height)
{
var file = _fileRep.GetFile(fileID);
byte[] newFile;
float ratioX = (float)width / (float)file.Width;
float ratioY = (float)height / (float)file.Height;
float ratio = Math.Min(ratioX, ratioY);
int newWidth = (int)(file.Width * ratio);
int newHeight = (int)(file.Height * ratio);
using (var resizedImage = new Bitmap(newWidth, newHeight))
{
using (var source = new Bitmap(new MemoryStream(file.FileContent)))
{
using (var g = Graphics.FromImage(resizedImage))
{
g.SmoothingMode = SmoothingMode.HighQuality;
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.DrawImage(source, 0, 0, newWidth, newHeight);
}
}
using (var ms = new MemoryStream())
{
resizedImage.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
newFile = ms.ToArray();
}
}
return new FileContentResult(newFile, "image/jpeg");
}
Result:
The right one is the exakt same picture but resized in photoshop.
How can I tune this to make quality much better?

First, try to save in a higher quality.
EncoderParameters ep = new EncoderParameters();
ep.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, (long)100);
foo.Save(filename, ici, ep);
If that is not satisfiable, you may need to use other libraries such as Emgu cv.
The grey problem may because that the color space (AdobeRGB or sRGB) of original image and the one you saved are not the same.

Using C# how can I resize a jpeg image?

Using C# how can I resize a jpeg image? A code sample would be great.

I'm using this:
public static void ResizeJpg(string path, int nWidth, int nHeight)
{
using (var result = new Bitmap(nWidth, nHeight))
{
using (var input = new Bitmap(path))
{
using (Graphics g = Graphics.FromImage((System.Drawing.Image)result))
{
g.DrawImage(input, 0, 0, nWidth, nHeight);
}
}
var ici = ImageCodecInfo.GetImageEncoders().FirstOrDefault(ie => ie.MimeType == "image/jpeg");
var eps = new EncoderParameters(1);
eps.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L);
result.Save(path, ici, eps);
}
}

Good free resize filter and example code.
http://code.google.com/p/zrlabs-yael/
private void MakeResizedImage(string fromFile, string toFile, int maxWidth, int maxHeight)
{
int width;
int height;
using (System.Drawing.Image image = System.Drawing.Image.FromFile(fromFile))
{
DetermineResizeRatio(maxWidth, maxHeight, image.Width, image.Height, out width, out height);
using (System.Drawing.Image thumbnailImage = image.GetThumbnailImage(width, height, new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallback), IntPtr.Zero))
{
if (image.Width < thumbnailImage.Width && image.Height < thumbnailImage.Height)
File.Copy(fromFile, toFile);
else
{
ImageCodecInfo ec = GetCodecInfo();
EncoderParameters parms = new EncoderParameters(1);
parms.Param[0] = new EncoderParameter(Encoder.Compression, 40);
ZRLabs.Yael.BasicFilters.ResizeFilter rf = new ZRLabs.Yael.BasicFilters.ResizeFilter();
//rf.KeepAspectRatio = true;
rf.Height = height;
rf.Width = width;
System.Drawing.Image img = rf.ExecuteFilter(System.Drawing.Image.FromFile(fromFile));
img.Save(toFile, ec, parms);
}
}
}
}

C# (or rather: the .NET framework) itself doesn't offer such capability, but it does offer you Bitmap from System.Drawing to easily access the raw pixel data of various picture formats. For the rest, see http://en.wikipedia.org/wiki/Image_scaling

Nice example.
public static Image ResizeImage(Image sourceImage, int maxWidth, int maxHeight)
{
// Determine which ratio is greater, the width or height, and use
// this to calculate the new width and height. Effectually constrains
// the proportions of the resized image to the proportions of the original.
double xRatio = (double)sourceImage.Width / maxWidth;
double yRatio = (double)sourceImage.Height / maxHeight;
double ratioToResizeImage = Math.Max(xRatio, yRatio);
int newWidth = (int)Math.Floor(sourceImage.Width / ratioToResizeImage);
int newHeight = (int)Math.Floor(sourceImage.Height / ratioToResizeImage);
// Create new image canvas -- use maxWidth and maxHeight in this function call if you wish
// to set the exact dimensions of the output image.
Bitmap newImage = new Bitmap(newWidth, newHeight, PixelFormat.Format32bppArgb);
// Render the new image, using a graphic object
using (Graphics newGraphic = Graphics.FromImage(newImage))
{
using (var wrapMode = new ImageAttributes())
{
wrapMode.SetWrapMode(WrapMode.TileFlipXY);
newGraphic.DrawImage(image, destRect, 0, 0, image.Width, image.Height, GraphicsUnit.Pixel, wrapMode);
}
// Set the background color to be transparent (can change this to any color)
newGraphic.Clear(Color.Transparent);
// Set the method of scaling to use -- HighQualityBicubic is said to have the best quality
newGraphic.InterpolationMode = InterpolationMode.HighQualityBicubic;
// Apply the transformation onto the new graphic
Rectangle sourceDimensions = new Rectangle(0, 0, sourceImage.Width, sourceImage.Height);
Rectangle destinationDimensions = new Rectangle(0, 0, newWidth, newHeight);
newGraphic.DrawImage(sourceImage, destinationDimensions, sourceDimensions, GraphicsUnit.Pixel);
}
// Image has been modified by all the references to it's related graphic above. Return changes.
return newImage;
}
Source : http://mattmeisinger.com/resize-image-c-sharp

ImageMagick should be the best way. Easy and reliable.
using (var image = new MagickImage(imgfilebuf))
{
image.Resize(len, len);
image.Strip();
using MemoryStream ms = new MemoryStream();
image.Write(ms);
return ms.ToArray();
}

Image resizing with GDI+

I'm really trying to nail out a little more performance out of this tidbit of code. It's not a heavly used bit of code but is used every time a new image is uploaded, and 4 times for each image (100px, 200px, 500px, 700px). So when there are any more than 2 or 3 images processing, it gets a little busy on the server. Also I'm trying to figure out how to make it correctly process images with a low resolution. Currently it just chops it off half way through, not plesent.
Examples: Original, large, xLarge
public static byte[] ResizeImageFile(byte[] imageFile, int targetSize)
{
using (System.Drawing.Image oldImage = System.Drawing.Image.FromStream(new MemoryStream(imageFile)))
{
Size newSize = CalculateDimensions(oldImage.Size, targetSize);
using (Bitmap newImage = new Bitmap(newSize.Width, newSize.Height, PixelFormat.Format32bppRgb))
{
newImage.SetResolution(oldImage.HorizontalResolution, oldImage.VerticalResolution);
using (Graphics canvas = Graphics.FromImage(newImage))
{
canvas.SmoothingMode = SmoothingMode.AntiAlias;
canvas.InterpolationMode = InterpolationMode.HighQualityBicubic;
canvas.PixelOffsetMode = PixelOffsetMode.HighQuality;
canvas.DrawImage(oldImage, new Rectangle(new Point(0, 0), newSize));
MemoryStream m = new MemoryStream();
newImage.Save(m, ImageFormat.Jpeg);
return m.GetBuffer();
}
}
}
}
private static Size CalculateDimensions(Size oldSize, int targetSize)
{
Size newSize = new Size();
if (oldSize.Width > oldSize.Height)
{
newSize.Width = targetSize;
newSize.Height = (int)(oldSize.Height * (float)targetSize / (float)oldSize.Width);
}
else
{
newSize.Width = (int)(oldSize.Width * (float)targetSize / (float)oldSize.Height);
newSize.Height = targetSize;
}
return newSize;
}
Thanks for and help!

The first thought that comes to mind is, have you thought about Multithreading it? i.e. calling this method for each image (or batch of images) in a separate thread? That way, if your server has a few cores you can get things done quicker. Just a thought...

(Threading is a great tip.)
Try to call your method with the smallest possible image as input each time, instead of the original image. If the original image is, say 2000px, then create the 700px image from it and then use your newly created 700px image to create the 500px, etc...
With the HighQualityBicubic setting I doubt that you'll notice any difference in the 100px image. (But it of course it needs to be verified.)

For completeness, here is the solution to the second part of the question which was never answered. When processing a low resolution image the image was being cut off. The solution now, seems obvious. The problem lies in this bit of code from above:
using (Bitmap newImage = new Bitmap(newSize.Width, newSize.Height,
PixelFormat.Format32bppRgb))
The problem being that I'm selecting the PixelFormat, not letting it be the format of the original image. The correct code is here:
public static byte[] ResizeImageFile(byte[] imageFile, int targetSize)
{
using (System.Drawing.Image oldImage = System.Drawing.Image.FromStream(new MemoryStream(imageFile)))
{
Size newSize = CalculateDimensions(oldImage.Size, targetSize);
using (Bitmap newImage = new Bitmap(newSize.Width, newSize.Height,
oldImage.PixelFormat))
{
newImage.SetResolution(oldImage.HorizontalResolution,
oldImage.VerticalResolution);
using (Graphics canvas = Graphics.FromImage(newImage))
{
canvas.SmoothingMode = SmoothingMode.AntiAlias;
canvas.InterpolationMode = InterpolationMode.HighQualityBicubic;
canvas.PixelOffsetMode = PixelOffsetMode.HighQuality;
canvas.DrawImage(oldImage, new Rectangle(new Point(0, 0), newSize));
MemoryStream m = new MemoryStream();
newImage.Save(m, ImageFormat.Jpeg);
return m.GetBuffer();
}
}
}
}

Why does resizing a png image lose transparency?

I am trying to resize an image as follows. I return the resized image into byte[] so that I can store it in database. The transparency of png image is lost. Please help to make this better.
private byte[] GetThumbNail(string imageFile, Stream imageStream,
int imageLen)
{
try
{
Image.GetThumbnailImageAbort imageCallBack =
new Image.GetThumbnailImageAbort(ThumbnailCallback);
Bitmap getBitmap = new Bitmap(imageFile);
byte[] returnByte = new byte[imageLen];
Image getThumbnail = getBitmap.GetThumbnailImage(160, 59,
imageCallBack, IntPtr.Zero);
using (Graphics g = Graphics.FromImage(getThumbnail))
{
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
g.InterpolationMode =
System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
g.DrawImage(getThumbnail, 0, 0, 160, 59);
}
using (MemoryStream ms = new MemoryStream())
{
getThumbnail.Save(ms, ImageFormat.Png);
getThumbnail.Save("test.png", ImageFormat.Png);
returnByte = ms.ToArray();
}
return returnByte;
}
catch (Exception)
{
throw;
}
}

Your code doesn't do quite what you think that it does...
You use the GetThumbnailImage to resize the image, then you draw the thumbnail image into itself which is rather pointless. You probably lose the transparency in the first step.
Create a blank bitmap instead, and resize the source image by drawing it on the blank bitmap.
private byte[] GetThumbNail(string imageFile) {
try {
byte[] result;
using (Image thumbnail = new Bitmap(160, 59)) {
using (Bitmap source = new Bitmap(imageFile)) {
using (Graphics g = Graphics.FromImage(thumbnail)) {
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
g.DrawImage(source, 0, 0, 160, 59);
}
}
using (MemoryStream ms = new MemoryStream()) {
thumbnail.Save(ms, ImageFormat.Png);
thumbnail.Save("test.png", ImageFormat.Png);
result = ms.ToArray();
}
}
return result;
} catch (Exception) {
throw;
}
}
(I removed some parameters that were never used for anything that had anything to do with the result, like the imageLen parameter that was only used to create a byte array that was never used.)

Try using the .MakeTransparent() call on your bitmap object.

May be you should do something like this because this thing worked for me:
String path = context.Server.MapPath("/images");
if (!path.EndsWith("\\"))
path += "\\";
path += "none.png";
Image img = CreateThumbnail(Image.FromFile(path));
MemoryStream ms = new MemoryStream();
img.Save(ms, ImageFormat.Png);
ms.WriteTo(context.Response.OutputStream);
private System.Drawing.Image CreateThumbnail(System.Drawing.Image i)
{
int dWidth = i.Width;
int dHeight = i.Height;
int dMaxSize = 150;
if (dWidth > dMaxSize)
{
dHeight = (dHeight * dMaxSize) / dWidth;
dWidth = dMaxSize;
}
if (dHeight > dMaxSize)
{
dWidth = (dWidth * dMaxSize) / dHeight;
dHeight = dMaxSize;
}
return i.GetThumbnailImage(dWidth, dHeight, delegate() { return false; }, IntPtr.Zero);
}