Making image thumbnail smaller - c#

I am having image sharing application where users upload images and I take thumbnails of these images...how ever , everything is working fine but sometimes the image thumbnail(600 * 800) size is almost 1 mb which is very huge is there anyway to modify the image resolution or something to make the size like..100 kb or something . this is my code .
Bitmap bmp = new Bitmap(Width, Height);
System.Drawing.Graphics gr = System.Drawing.Graphics.FromImage(bmp);
gr.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
gr.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
gr.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
gr.PixelOffsetMode = PixelOffsetMode.HighQuality;
System.Drawing.Rectangle rectDestination = new System.Drawing.Rectangle(0, 0, Width, Height);
System.Drawing.Size rs = new System.Drawing.Size();
rs.Height = Height;
rs.Width = Width;
gr.DrawImage(originalImage, new Rectangle(new Point(0, 0), rs), 0, 0, originalImage.Width, originalImage.Height, GraphicsUnit.Pixel);
string thumbnailPath = string.Concat(pathToSaveIn, thumbnailName);
bmp.Save(thumbnailPath);
gr.Dispose();


The image resizing code looks OK (at first glance). However, you're saving the image in bitmap format, which is lossless -- hence the large size of the file.
You probably want to use JPEG instead for a thumbnail: for photographs, etc., this gives good compression.
This may help:
public void SaveImage(Bitmap image, string filename)
{
long quality = 80L; // adjust as appropriate
var qualityEncoder = Encoder.Quality;
using (var encoderParameter = new EncoderParameter(qualityEncoder, quality))
using (var encoderParams = new EncoderParameters(1))
{
encoderParams.Param[0] = encoderParameter;
var jpegEncoder = GetEncoder(ImageFormat.Jpeg);
image.Save(filename, jpegEncoder, encoderParams);
}
}
private static ImageCodecInfo GetEncoder(ImageFormat format)
{
ImageCodecInfo[] codecs = ImageCodecInfo.GetImageDecoders();
return codecs
.Where(codec => codec.FormatID == format.Guid)
.FirstOrDefault();
}


This looks like .NET. Scott Hanselman had a good blog post on this. Essentially a review of a package on NuGet that helps with this.
http://www.hanselman.com/blog/NuGetPackageOfWeek11ImageResizerEnablesCleanClearImageResizingInASPNET.aspx


Try System.Drawing.Image.GetThumbnailImage. I haven't used it myself, but looks like it might work.

Related

Why does my image resize code always product a completely black output image?

I'm trying to resize an image. I thought it was a simple task...
Here's my code (note, the two Save calls are just for debugging to illustrate the problem):
var newSize = new Size { Width = 450, Height = 250 };
using (var img = (Bitmap)Image.FromFile(sourceImageFilename))
{
var outputImage = new Bitmap(newSize.Width, newSize.Height);
// Save input image for debugging (screenshot below)
img.Save(#"M:\Coding\Photos\Temp\input.jpg");
using (Graphics gr = Graphics.FromImage(img))
{
gr.SmoothingMode = SmoothingMode.HighQuality;
gr.InterpolationMode = InterpolationMode.HighQualityBicubic;
gr.PixelOffsetMode = PixelOffsetMode.HighQuality;
gr.DrawImage(outputImage, new Rectangle(0, 0, newSize.Width, newSize.Height));
}
// Save output image for debugging (screenshot below)
outputImage.Save(#"M:\Coding\Photos\Temp\output.jpg");
}
This appears to be the exact same code a ton of people are using (and exists on SO in many answers). However, here's what the two images that are being written to disk look like:
The original image is 5344x3006 and newSize (and the black output image) are 450x250.
All my other code is working fine (reading pixels from the input image with SetPixel, etc.), it's just this resize that's broken. Doing the resize with the Bitmap constructor is fine (but a bad quality resize).

You need to get the graphics from the OutputImage.
public static Bitmap Scale(this Bitmap inputImage, Size newSize)
{
var outputImage = new Bitmap(newSize.Width, newSize.Height);
inputImage.Save(#"M:\Coding\Photos\Temp\input.jpg");
using (Graphics gr = Graphics.FromImage(outputImage))
{
gr.SmoothingMode = SmoothingMode.HighQuality;
gr.InterpolationMode = InterpolationMode.HighQualityBicubic;
gr.PixelOffsetMode = PixelOffsetMode.HighQuality;
gr.DrawImage(inputImage, new Rectangle(0, 0, newSize.Width, newSize.Height));
}
outputImage.Save(#"M:\Coding\Photos\Temp\output.jpg");
return outputImage;
}

C# change dpi of an uploaded image

I've got to following function which is called to change the resolution of an image. I want to do this so uploaded image with for example 300dpi will be modified to 72dpi (for web). This question is related to another question here on SO where i'm working on.
I'm creation an extension method for this to be able to use this function on more places in my application, instead of only when uploading new files. (See above mentioned question)
public static byte[] SetDpiTo72(this byte[] imageToFit, string mimeType, Size newSize)
{
using (MemoryStream memoryStream = new MemoryStream(), newMemoryStream = new MemoryStream())
{
memoryStream.Write(imageToFit, 0, imageToFit.Length);
var originalImage = new Bitmap(memoryStream);
using (var canvas = Graphics.FromImage(originalImage))
{
canvas.SmoothingMode = SmoothingMode.AntiAlias;
canvas.InterpolationMode = InterpolationMode.HighQualityBicubic;
canvas.PixelOffsetMode = PixelOffsetMode.HighQuality;
canvas.DrawImage((Image)originalImage,0,0, newSize.Width, newSize.Height);
newBitmap.SetResolution(72, 72);
newBitmap.Save(newMemoryStream, ImageFunctions.GetEncoderInfo(mimeType), null);
}
return newMemoryStream.ToArray();
}
}
The mentioned extension methode is being called in a function similar to the situation below;
if (newSize.Width > originalImage.Width && newSize.Height > originalImage.Height)
{
newSize.Width = originalImage.Width;
newSize.Height = originalImage.Height;
uploadedFileBuffer = uploadedFileBuffer.SetDpiTo72(uploadedFile.ContentType, newSize);
return CreateFile(newSize, uploadedFile, uploadedFileBuffer);
}
The bytearray coming in is the file as an bytearray. It already has the correct size, but I want to change the resolution to 72dpi. However after exectution and saving the image the resolution is still the originale entered resolution, which is 300dpi. How can I do this?
UPDATE AFTER SEVERAL ANSWERS:
public static byte[] SetDpiTo72(this byte[] imageToFit, string mimeType, Size newSize)
{
using (MemoryStream memoryStream = new MemoryStream(), newMemoryStream = new MemoryStream())
{
memoryStream.Write(imageToFit, 0, imageToFit.Length);
var originalImage = new Bitmap(memoryStream);
using (var canvas = Graphics.FromImage(originalImage))
{
canvas.SmoothingMode = SmoothingMode.AntiAlias;
canvas.InterpolationMode = InterpolationMode.HighQualityBicubic;
canvas.PixelOffsetMode = PixelOffsetMode.HighQuality;
canvas.DrawImage((Image)originalImage,0,0, newSize.Width, newSize.Height);
originalImage.SetResolution(72, 72);
var epQuality = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 75);
var epParameters = new EncoderParameters(1);
epParameters.Param[0] = epQuality;
Image newimg = Image.FromStream(memoryStream);
//Getting an GDI+ exception after the execution of this line.
newimg.Save("C:\\test1234.jpg", ImageFunctions.GetEncoderInfo(mimeType), epParameters);
originalImage.Save("test.jpg", ImageFormat.Jpeg);
//This line give me an Argumentexception - Parameter is not valid.
//originalImage.Save(newMemoryStream, ImageFunctions.GetEncoderInfo(mimeType), epParameters);
//newMemoryStream.Close();
}
return newMemoryStream.ToArray();
}
}
The stackstrace which comes with the exception is telling me the following;
at System.Drawing.Image.Save(String filename, ImageCodecInfo encoder, EncoderParameters encoderParams)
at Extensions.ByteArrayExtensions.SetDpiTo72(Byte[] imageToFit, String mimeType, Size newSize) in C:\Website\Project\Extensions\ByteArrayExtensions.cs:line 356
at CMS.Presentation.FileFunctions.CreateFullsizeImage(HttpPostedFileBase uploadedFile, Size newSize, Byte[] uploadedFileBuffer) in C:\Website\Project\CMS.Presentation\FileFunctions.cs:line 197
at CMS.Presentation.FileFunctions.CreateFile(HttpPostedFileBase uploadedFile, INodeService nodeservice, Guid userId, Node parentNode) in C:\Website\Project\CMS.Presentation\FileFunctions.cs:line 53
In the mean time I've also developed another function (see below) resizing just a bitmap. And this seem to work correctly. I can't use this function with my current implementation though because it returns just an Bitmap. Or should i change everything to work with bitmaps?
private static Bitmap ResizeImage(Image image, int width, int height)
{
var frameCount = image.GetFrameCount(new FrameDimension(image.FrameDimensionsList[0]));
var newDimensions = ImageFunctions.GenerateImageDimensions(image.Width, image.Height, width, height);
Bitmap resizedImage;
if (frameCount > 1)
{
//we have a animated GIF
resizedImage = ResizeAnimatedGifImage(image, width, height);
}
else
{
resizedImage = (Bitmap)image.GetThumbnailImage(newDimensions.Width, newDimensions.Height, null, IntPtr.Zero);
}
resizedImage.SetResolution(72,72);
return resizedImage;
}

Ok, I tried it only on files on harddrive, but it should work with streams too.
Bitmap bitmap = new Bitmap(loadFrom);
Bitmap newBitmap = new Bitmap(bitmap);
newBitmap.SetResolution(72, 72);
newBitmap.Save(saveTo);

Took me a while, but I finally found the problem!
The problem lied in the ResizeImage function I used. In the 'GetThumbnailImage' to be specific. I ran into another problem with blurry images, which was explainable because GetThumbnailImage would stretch up the created ThumbNail to the desired size. And the resolution off the thumbnail never changes.
private static Bitmap ResizeImage(Image image, int width, int height)
{
var frameCount = image.GetFrameCount(new FrameDimension(image.FrameDimensionsList[0]));
var newDimensions = ImageFunctions.GenerateImageDimensions(image.Width, image.Height, width, height);
Bitmap resizedImage;
if (frameCount > 1)
{
//we have a animated GIF
resizedImage = ResizeAnimatedGifImage(image, width, height);
}
else
{
resizedImage = (Bitmap)image.GetThumbnailImage(newDimensions.Width, newDimensions.Height, null, IntPtr.Zero);
}
resizedImage.SetResolution(72,72);
return resizedImage;
}
By modifying the function above to the function below I was able to solve the problem using Graphics.DrawImage to redraw the new image before rendering it. Also the GenerateImageDimensions was slightly modified. This taken together the problem was solved.
private static Bitmap ResizeImage(Image image, int width, int height)
{
var frameCount = image.GetFrameCount(new FrameDimension(image.FrameDimensionsList[0]));
var newDimensions = ImageFunctions.GenerateImageDimensions(image.Width, image.Height, width, height);
var resizedImage = new Bitmap(newDimensions.Width, newDimensions.Height);
if (frameCount > 1)
{
//we have a animated GIF
resizedImage = ResizeAnimatedGifImage(image, width, height);
}
else
{
//we have a normal image
using (var gfx = Graphics.FromImage(resizedImage))
{
gfx.SmoothingMode = SmoothingMode.HighQuality;
gfx.InterpolationMode = InterpolationMode.HighQualityBicubic;
gfx.PixelOffsetMode = PixelOffsetMode.HighQuality;
var targRectangle = new Rectangle(0, 0, newDimensions.Width, newDimensions.Height);
var srcRectangle = new Rectangle(0, 0, image.Width, image.Height);
gfx.DrawImage(image, targRectangle, srcRectangle, GraphicsUnit.Pixel);
}
}
return resizedImage;
}

By "changing the resolution", do you actually mean you want to reduce the number of pixels in the image by 72/300? I.e. change a 4000x3000 image to 960x720?
If so, I can't see where your code actually does that. The overload of DrawImage() you're using does this:
Draws the specified image, using its original physical size, at the location specified by a coordinate pair.
Which is exactly what is happening.
Try one of the other overloads such as this one:
Draws the specified Image at the specified location and with the specified size.
for example:
// Create image.
Image newImage = Image.FromFile("SampImag.jpg");
// Create coordinates for upper-left corner of image and for size of image.
int x = 0;
int y = 0;
int width = 450;
int height = 150;
// Draw image to screen.
e.Graphics.DrawImage(newImage, x, y, width, height);
EDIT: per the comments, I understand the OP wants to reduce file size without reducing pixel count. Therefore the files must be recompressed.
I've borrowed some sample code from here:
ImageCodecInfo iciJpegCodec = null;
// This will specify the image quality to the encoder. Change the value of 75 from 0 to 100, where 100 is best quality, but highest file size.
EncoderParameter epQuality = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 75);
// Get all image codecs that are available
ImageCodecInfo[] iciCodecs = ImageCodecInfo.GetImageEncoders();
// Store the quality parameter in the list of encoder parameters
EncoderParameters epParameters = new EncoderParameters(1);
epParameters.Param[0] = epQuality;
// Loop through all the image codecs
for (int i = 0; i < iciCodecs.Length; i++)
{
// Until the one that we are interested in is found, which is image/jpeg
if (iciCodecs[i].MimeType == "image/jpeg")
{
iciJpegCodec = iciCodecs[i];
break;
}
}
// Create a new Image object from the current file
Image newImage = Image.FromFile(strFile);
// Get the file information again, this time we want to find out the extension
FileInfo fiPicture = new FileInfo(strFile);
// Save the new file at the selected path with the specified encoder parameters, and reuse the same file name
newImage.Save(outputPath + "\\" + fiPicture.Name, iciJpegCodec, epParameters);

Rob, I believe that issue with your code is at saving the image - the actual digital image data would be certain number of dots/pixels i.e. (m x n) and setting resolution at bitmap wouldn't/shouldn't change the number dots (and hence physical byte size of image). The resolution information will be stored in the image header (to be used by programs while printing/editing images) - what happens if you store the new bitmap to file instead of mem stream
newBitmap.Save("c:\test.png", ImageFormat.Png);
Check dpi for above file from file -> properties -> summary (advanced). It should be 72 dpi.

Alpha channel transparency and resizing image files

I'm using the following code to resize a tif. The tif has an alpha channel set for transparency. I'm trying to resize this image and honour the transparency but at the moment it's coming out with a black background. Any ideas?
public static void ResizeImage(string OriginalImagePath, string NewImagePath, int Width, int Height)
{
Size NewSize = new Size(Width, Height);
using (Image OriginalImage = Image.FromFile(OriginalImagePath))
{
//Graphics objects can not be created from bitmaps with an Indexed Pixel Format, use RGB instead.
PixelFormat Format = OriginalImage.PixelFormat;
if (Format.ToString().Contains("Indexed"))
Format = PixelFormat.Format24bppRgb;
using (Bitmap NewImage = new Bitmap(NewSize.Width, NewSize.Height, OriginalImage.PixelFormat))
{
using (Graphics Canvas = Graphics.FromImage(NewImage))
{
Canvas.SmoothingMode = SmoothingMode.AntiAlias;
Canvas.InterpolationMode = InterpolationMode.HighQualityBicubic;
Canvas.PixelOffsetMode = PixelOffsetMode.HighQuality;
Canvas.DrawImage(OriginalImage, new Rectangle(new Point(0, 0), NewSize));
NewImage.Save(NewImagePath, OriginalImage.RawFormat);
}
}
}
}
}

Try this:
if (Format.ToString().Contains("Indexed"))
Format = PixelFormat.Format32bppArgb;
Format32bppArgb specifies an alpha channel in the pixel format.
And I think you meant to do this:
using (Bitmap NewImage = new Bitmap(NewSize.Width, NewSize.Height, Format))
EDIT:
Actually, try just forcing the pixel format on the NewImage to Format32bppArgb like so:
using (Bitmap NewImage = new Bitmap(NewSize.Width, NewSize.Height,
PixelFormat.Format32bppArgb))

Canvas.Clear(Color.Transparent)
before you blit.

I actually found out that due to the way the transparency is stored in the tiff format with photoshop it was better to create png's by automating photoshop and then crunching off the resulting png.

C# generating thumbnails filesize

I have the following code to take an image and generate the thumbnail.
how can I alter the quality or compression to get smaller file sizes programatically?
Image thumbNail = image.GetThumbnailImage(Width, Height, null, new IntPtr());

If you truly need better control over the thumbnails produced, you will be better off producing your own by manually generating an image of smaller size and different quality. The GetThumbnailImage dows not give you much control.
See this article for how it's done.
http://www.switchonthecode.com/tutorials/csharp-tutorial-image-editing-saving-cropping-and-resizing

When saving the thumbNail with Image.Save you can specify the quality by passing a EncoderParameter. See: Reducing JPEG Picture Quality using C#
EncoderParameter epQuality = new EncoderParameter(
System.Drawing.Imaging.Encoder.Quality,
(int)numQual.Value);
...
newImage.Save(..., iciJpegCodec, epParameters);

You do not use the GetThumbnailImage API:
protected Stream ResizeImage(string source, int width, int height) {
using (System.Drawing.Bitmap bmp = (System.Drawing.Bitmap)System.Drawing.Bitmap.FromFile(source))
using (System.Drawing.Bitmap newBmp = new System.Drawing.Bitmap(width, height))
using (System.Drawing.Graphics graphic = System.Drawing.Graphics.FromImage(newBmp))
{
graphic.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
graphic.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
graphic.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.HighQuality;
graphic.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
graphic.DrawImage(bmp, 0, 0, width, height);
MemoryStream ms = new MemoryStream();
newBmp.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
return ms;
}
}

Why does the PngBitmapEncoder class make my images look grainy?

I'm using this code to convert a jpg image into a png 8.
The code works but the image looks grainy. I did an export in Photoshop as png 8 and it looks smoother and no grain.
Note: 8-bit png
Any image gurus out there that can help?
My code:
Image ImageFile = Image.FromFile(#"C:\Documents and Settings\dvela\My Documents\Downloads\pngtest\Batman01.jpg");
Rectangle NewSize = new Rectangle();
NewSize.Width = 112;
NewSize.Height = (NewSize.Width * ImageFile.Height) / ImageFile.Width;
Bitmap image = new Bitmap(NewSize.Width, NewSize.Height);
Graphics graphics = Graphics.FromImage(image);
graphics.CompositingQuality = CompositingQuality.HighQuality;
graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;
graphics.SmoothingMode = SmoothingMode.HighQuality;
graphics.DrawImage(ImageFile, NewSize);
FormatConvertedBitmap fcb = new FormatConvertedBitmap(System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(image.GetHbitmap(), IntPtr.Zero, Int32Rect.Empty, BitmapSizeOptions.FromWidthAndHeight(NewSize.Width, NewSize.Height)), PixelFormats.Indexed8, BitmapPalettes.Halftone256Transparent, 0.5);
PngBitmapEncoder pngBitmapEncoder = new PngBitmapEncoder();
pngBitmapEncoder.Interlace = PngInterlaceOption.Off;
pngBitmapEncoder.Frames.Add(BitmapFrame.Create(fcb));
using (Stream fileStream = File.Open(#"C:\Documents and Settings\dvela\My Documents\Downloads\pngtest\test.png", FileMode.Create))
{
pngBitmapEncoder.Save(fileStream);
}

You are using a fixed palette with 256 colors for your converted image. Photoshop probably uses a palette that is created specially for that image and contains all of it's colors (or most of them).
You could use dithering, or somehow generate a custom palette, or both.
some more information is also here.

I found this library that does Palette-based and Octree-based color Quantization.
This MSDN article explains the difference between the algorithms with code.

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