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How can I convert a BMP to JPEG without saving to file?

I have a BMP image object which contains a BMP image, how can I convert it to JPEG format without saving to file?
All I need to know is the size of the JPEG file after the conversion, so If I have several BMP images, I want to convert each one of them into a JPEG and then see the size of each one.
How can I do that?
Thanks.

Just save it stream. and look size.
private ImageCodecInfo GetEncoder(ImageFormat format)
{
ImageCodecInfo[] codecs = ImageCodecInfo.GetImageDecoders();
foreach (ImageCodecInfo codec in codecs)
{
if (codec.FormatID == format.Guid)
{
return codec;
}
}
return null;
}
private void Form1_Load(object sender, EventArgs e)
{
Bitmap bmp1 = new Bitmap(#"C:\Users\ercan.acar\Pictures\Current CR Sticker.PNG");
ImageCodecInfo jpgEncoder = GetEncoder(ImageFormat.Jpeg);
System.Drawing.Imaging.Encoder myEncoder =System.Drawing.Imaging.Encoder.Quality;
EncoderParameters myEncoderParameters = new EncoderParameters(1);
EncoderParameter myEncoderParameter = new EncoderParameter(myEncoder,
50L);
myEncoderParameters.Param[0] = myEncoderParameter;
Stream stream=new MemoryStream();
bmp1.Save(stream, jpgEncoder,myEncoderParameters);
//bmp1.Save(#"C:\Users\ercan.acar\Documents\TestPhotoQualityFifty.jpg",);
var size = stream.Length;
}

How about using a nuget package like Magick.NET or similar.
Why reinventing the wheel and care about encoding, conversion adjustments, optimization if other have done this already for you.

Tiff Image :How to set metadata for the mulltipage tiff programatically in .Net?

I am trying to set metadata for multi-page tiff image. Below is code snippet setting metadata for single-page tiff image.
Bitmap imageSource = img as Bitmap; // img is an original singlepage tiff image
Bitmap tempBitmap = new Bitmap(imageSource.Width, imageSource.Height);
try
{
ImageCodecInfo encoderInfo = GetEncoderInfo("image/tiff");
EncoderParameters encoderParams = new EncoderParameters(2);
EncoderParameter parameter = new EncoderParameter(System.Drawing.Imaging.Encoder.Compression, (long)EncoderValue.CompressionCCITT3);
encoderParams.Param[0] = parameter;
parameter = new EncoderParameter(System.Drawing.Imaging.Encoder.SaveFlag,(long)EncoderValue.Flush);
encoderParams.Param[1] = parameter;
//Set the resolution as of the image file
tempBitmap.SetResolution(imageSource.HorizontalResolution, imageSource.VerticalResolution);
using (Graphics graphics = Graphics.FromImage(tempBitmap))
{
//Draw the image in the Empty bitmap by passing original imageSource
graphics.DrawImage(imageSource, 0, 0, (float)imageSource.Width, (float)imageSource.Height);
}
string strSign = "I am author";
PropertyItem propItem = img.PropertyItems[0];
propItem.Id = 315; // this is called 'Author'
propItem.Type = 2;
propItem.Value = System.Text.Encoding.UTF8.GetBytes(strSign + "\0");//signature;
propItem.Len = propItem.Value.Length;
((Image)tempBitmap).SetPropertyItem(propItem);
img.Dispose();
((Image)tempBitmap).Save("sample.tif", encoderInfo, encoderParams);
}
catch (Exception ex)
{
}
This above code works fine for single-page image, but cant achieve setting metadata for multi-page image. I am bit new to this, any useful links or libraries available to achieve setting matadata for multi-page tiff image would be helpful.

Compress image without saving it

I am using the following code to compress an image and it does a nice job but I want to use the compressed image not save it. So right now I have to save the image then read it in again which is slow. Is there a way of compressing it with out saving it.
private void compress(System.Drawing.Image img, long quality, ImageCodecInfo codec)
{
EncoderParameters parameters = new EncoderParameters(1);
parameters.Param[0] = new EncoderParameter(Encoder.Quality, quality);
img.Save("check1.jpg", codec, parameters);
}
private static ImageCodecInfo GetCodecInfo(string mimeType)
{
foreach (ImageCodecInfo encoder in ImageCodecInfo.GetImageEncoders())
if (encoder.MimeType == mimeType)
return encoder;
throw new ArgumentOutOfRangeException(
string.Format("'{0}' not supported", mimeType));
}

There is an overload that takes a Stream so you can save it straight to a MemoryStream and won't need to save to disk/reload.
EncoderParameters parameters = new EncoderParameters(1);
parameters.Param[0] = new EncoderParameter(Encoder.Quality, quality);
var ms = new MemoryStream();
img.Save(ms, codec, parameters);
//Do whatever you need to do with the image
//e.g.
img = Image.FromStream(ms);
The reason you're getting the "Parameter not valid" exception you mention in the comments is because the image isn't being disposed of before you try to call FromStream, so you'll need to dispose it. Also, I don't know how you're calling this method, but you should probably update it to return the MemoryStream.
private MemoryStream compress(System.Drawing.Image img, long quality, ImageCodecInfo codec)
{
EncoderParameters parameters = new EncoderParameters(1);
parameters.Param[0] = new EncoderParameter(Encoder.Quality, quality);
var ms = new MemoryStream();
img.Save(ms, codec, parameters);
return ms;
}
public void MyMethod()
{
MemoryStream ms;
using(var img = Image.FromFile("myfilepath.img"))
{
ms = compress(img, /*quality*/, /*codec*/);
}
using(var compressedImage = Image.FromStream(ms))
{
//Use compressedImage
}
}
Notice how I return ms from compress and capture it. Also, more importantly, how we wrap the initial img in a using statement which will dispose the file handle correctly, and after that gets disposed create the second compressedImage which is also in a using so it will also get disposed of properly when you're done.

Image compression is not working

I have an operation on the site that takes crops an image, however the resultant, cropped image is coming out significantly larger in terms of file size (original is 24k and the cropped image is like 650k). So I found that I need to apply some compression to the image before saving it. I came up with the following:
public static System.Drawing.Image CropImage(System.Drawing.Image image, Rectangle cropRectangle, ImageFormat format)
{
var croppedImage = new Bitmap(cropRectangle.Width, cropRectangle.Height);
using (var g = Graphics.FromImage(croppedImage))
{
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.DrawImage(
image,
new Rectangle(new Point(0,0), new Size(cropRectangle.Width, cropRectangle.Height)),
cropRectangle,
GraphicsUnit.Pixel);
return CompressImage(croppedImage, format);
}
}
public static System.Drawing.Image CompressImage(System.Drawing.Image image, ImageFormat imageFormat)
{
var bmp = new Bitmap(image);
var codecInfo = EncoderFactory.GetEncoderInfo(imageFormat);
var encoder = System.Drawing.Imaging.Encoder.Quality;
var parameters = new EncoderParameters(1);
var parameter = new EncoderParameter(encoder, 10L);
parameters.Param[0] = parameter;
using (var ms = new MemoryStream())
{
bmp.Save(ms, codecInfo, parameters);
var resultImage = System.Drawing.Image.FromStream(ms);
return resultImage;
}
}
I set the quality low just to see if there was any change at all. There isn't. The crop is being saved correctly appearance-wise but compression is a no joy. If I bypass CompressImage() altogether, neither the file size nor the image quality appear to be any different.
So, 2 questions. Why is nothing happening? Is there a simpler way to compress the resultant image to "web-optimize" similar to how photoshop saves web images (I thought it just stripped a lot of info out of it to reduce the size).

Your problem is you must 'compress' (really encode) the image as you save it, not before you save it. An Image object in your program is always uncompressed.
By saving to the MemoryStream and reading back out from the stream will encode the image and then decode it back to the same size again (with some quality loss in the process if you are using JPEG). However, if you save it to a file with the compression parameters, you will get a compressed image file.
Using this routine with JPEG quality level 90 on a 153 KB source image gives an output image of 102 KB. If you want a smaller file size (with more encoding artifacts) change the encoder parameter to something smaller than 90.
public static void SaveJpegImage(System.Drawing.Image image, string fileName)
{
ImageCodecInfo codecInfo = ImageCodecInfo.GetImageEncoders()
.Where(r => r.CodecName.ToUpperInvariant().Contains("JPEG"))
.Select(r => r).FirstOrDefault();
var encoder = System.Drawing.Imaging.Encoder.Quality;
var parameters = new EncoderParameters(1);
var parameter = new EncoderParameter(encoder, 90L);
parameters.Param[0] = parameter;
using (FileStream fs = new FileStream(fileName, FileMode.Create))
{
image.Save(fs, codecInfo, parameters);
}
}

I believe you shouldn't dispose of the MemoryStream while you are using an image created using Image.FromStream that refers to the stream. Creating a Bitmap directly from the stream also doesn't work.
Try this:
private static Image CropAndCompressImage(Image image, Rectangle rectangle, ImageFormat imageFormat)
{
using(Bitmap bitmap = new Bitmap(image))
{
using(Bitmap cropped = bitmap.Clone(rectangle, bitmap.PixelFormat))
{
using (MemoryStream memoryStream = new MemoryStream())
{
cropped.Save(memoryStream, imageFormat);
return new Bitmap(Image.FromStream(memoryStream));
}
}
}
}

Bmp to jpg/png in C#

Is there any way to convert a bmp image to jpg/png without losing the quality in C#? Using Image class we can convert bmp to jpg but the quality of output image is very poor. Can we gain the quality level as good as an image converted to jpg using photoshop with highest quality?

var qualityEncoder = Encoder.Quality;
var quality = (long)<desired quality>;
var ratio = new EncoderParameter(qualityEncoder, quality );
var codecParams = new EncoderParameters(1);
codecParams.Param[0] = ratio;
var jpegCodecInfo = <one of the codec infos from ImageCodecInfo.GetImageEncoders() with mime type = "image/jpeg">;
bmp.Save(fileName, jpegCodecInfo, codecParams); // Save to JPG

public static class BitmapExtensions
{
public static void SaveJPG100(this Bitmap bmp, string filename)
{
EncoderParameters encoderParameters = new EncoderParameters(1);
encoderParameters.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L);
bmp.Save(filename, GetEncoder(ImageFormat.Jpeg), encoderParameters);
}
public static void SaveJPG100(this Bitmap bmp, Stream stream)
{
EncoderParameters encoderParameters = new EncoderParameters(1);
encoderParameters.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L);
bmp.Save(stream, GetEncoder(ImageFormat.Jpeg), encoderParameters);
}
public static ImageCodecInfo GetEncoder(ImageFormat format)
{
ImageCodecInfo[] codecs = ImageCodecInfo.GetImageDecoders();
foreach (ImageCodecInfo codec in codecs)
{
if (codec.FormatID == format.Guid)
{
return codec;
}
}
return null;
}
}

Provided BitmapExtensions by jestro are great, I used them. However would like to show the corrected version - works for Image parent class which is more convenient as I think and provides a way to supply quality:
public static class ImageExtensions
{
public static void SaveJpeg(this Image img, string filePath, long quality)
{
var encoderParameters = new EncoderParameters(1);
encoderParameters.Param[0] = new EncoderParameter(Encoder.Quality, quality);
img.Save(filePath, GetEncoder(ImageFormat.Jpeg), encoderParameters);
}
public static void SaveJpeg(this Image img, Stream stream, long quality)
{
var encoderParameters = new EncoderParameters(1);
encoderParameters.Param[0] = new EncoderParameter(Encoder.Quality, quality);
img.Save(stream, GetEncoder(ImageFormat.Jpeg), encoderParameters);
}
static ImageCodecInfo GetEncoder(ImageFormat format)
{
ImageCodecInfo[] codecs = ImageCodecInfo.GetImageDecoders();
return codecs.Single(codec => codec.FormatID == format.Guid);
}
}

Fundamentally you won't be able to keep the same quality because jpg is (so far as I'm aware) always lossy even with the highest possible quality settings.
If bit-accurate quality is really important, consider using png, which has some modes which are lossless.

Just want to say that JPEG is by nature a lossy format. So in thoery even at the highest settings you are going to have some information loss, but it depends a lot on the image.But png is lossless.

I am working on an expense report app, and I am really pleased with the default quality settings for JPG (and PNG) when saving from a Bitmap object.
https://msdn.microsoft.com/en-us/library/9t4syfhh%28v=vs.110%29.aspx
Bitmap finalBitmap = ....; //from disk or whatever
finalBitmap.Save(xpsFileName + ".final.jpg", ImageFormat.Jpeg);
finalBitmap.Save(xpsFileName + ".final.png", ImageFormat.Png);
I'm on .NET 4.6...perhaps the quality has improved in subsequent framework releases.

You can try:
Bitmap.InterpolationMode = InterpolationMode.HighQualityBicubic;
and
Bitmap.CompositingQuality = CompositingQuality.HighQuality;
Which does keep the quality fairly high, but not the highest possible.