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C# lower quality for JPEG image

I'm trying to make an console application in .net core 3, this application can successfully get a bitmap from the computer and send it to another computer. But now I want to lower the quality of the image and send it as a JPEG file.
I have looked on the internet but I'm unable to get it to work. My latest attempt I tried to use the following MSDN website. But with this approach I get stuck at ImageCodecInfo jpgEncoder = GetEncoder(ImageFormat.Jpeg); since my application cannot find GetEncoder. I have found GetEncoder in System.Text.Encoding.Getencoding but here getEncoder doesn't take any parameters.
So my question is which namespace do I have to use or is there another way to lower the quality of an JPEG image?

Here is my functions to compress image as jpeg
public static System.Drawing.Imaging.ImageCodecInfo GetEncoder(System.Drawing.Imaging.ImageFormat format)
{
System.Drawing.Imaging.ImageCodecInfo[] codecs = System.Drawing.Imaging.ImageCodecInfo.GetImageDecoders();
foreach (System.Drawing.Imaging.ImageCodecInfo codec in codecs)
{
if (codec.FormatID == format.Guid)
{
return codec;
}
}
return null;
}
public static byte[] GetCompressedImage(System.Drawing.Image img, long quality)
{
System.Drawing.Imaging.ImageCodecInfo ici = GetEncoder(System.Drawing.Imaging.ImageFormat.Jpeg);
System.Drawing.Imaging.EncoderParameters eps = new System.Drawing.Imaging.EncoderParameters(2);
eps.Param[0] = new System.Drawing.Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality);
eps.Param[1] = new System.Drawing.Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.Compression, (long)System.Drawing.Imaging.EncoderValue.CompressionLZW);
using (MemoryStream ms = new MemoryStream())
{
img.Save(ms, ici, eps);
return ms.ToArray();
}
}

Change resolution of jpeg image using c#

I am trying to change resolution of my jpg image using c#.
I have refer this code that written in this link How to change resolution (DPI) of an image? its work fine but I have getting another issue for grayscale images.
if I will try to save grayscale image using this code then it change the bit depth 8 to 24.
So I have try below code but I am getting error like "Bitmap region is already locked". I don't know how to pass guid in GetEncoderParameterList().
private static ImageCodecInfo GetEncoder(ImageFormat format)
{
ImageCodecInfo[] codecs = ImageCodecInfo.GetImageDecoders();
foreach (ImageCodecInfo codec in codecs)
{
if (codec.FormatID == format.Guid)
{
return codec;
}
}
return null;
}
//Code
using (Image bitmap = Image.FromFile(pagePath))
{
using (Bitmap newBitmap = new Bitmap(bitmap))
{
ImageCodecInfo jpgEncoder = GetEncoder(ImageFormat.Jpeg);
EncoderParameters para = newBitmap.GetEncoderParameterList(jpgEncoder.Clsid);
imageResolution = (int)newBitmap.HorizontalResolution;
newBitmap.SetResolution(250, 250);
newBitmap.Save("file300.jpg", jpgEncoder, para);
}
}
Exception :

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));
}
}
}
}

Compress bitmap before sending over network

I'm trying to send a bitmap screenshot over network, so I need to compress it before sending it. Is there a library or method for doing this?

When you save an Image to a stream, you have to select a format. Almost all bitmap formats (bmp, gif, jpg, png) use 1 or more forms of compression. So just select an appropriate format, and make make sure that sender and receiver agree on it.

If you are looking for something to compress the image in quality, here it is-
private Image GetCompressedBitmap(Bitmap bmp, long quality)
{
using (var mss = new MemoryStream())
{
EncoderParameter qualityParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality);
ImageCodecInfo imageCodec = ImageCodecInfo.GetImageEncoders().FirstOrDefault(o => o.FormatID == ImageFormat.Jpeg.Guid);
EncoderParameters parameters = new EncoderParameters(1);
parameters.Param[0] = qualityParam;
bmp.Save(mss, imageCodec, parameters);
return Image.FromStream(mss);
}
}
Use it -
var compressedBmp = GetCompressedBitmap(myBmp, 60L);

Try the System.IO.DeflateStream class.

May be you can use:
private Bitmap compressImage(Bitmap image) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
image.compress(Bitmap.CompressFormat.JPEG, 100, baos);//
int options = 100;
while ( baos.toByteArray().length / 1024>100) { //
baos.reset();
image.compress(Bitmap.CompressFormat.JPEG, options, baos);//
options -= 10;// 10
}
ByteArrayInputStream isBm = new ByteArrayInputStream(baos.toByteArray());//
Bitmap bitmap = BitmapFactory.decodeStream(isBm, null, null);//
return bitmap;
}

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.