I have a byte[] for an image, which was read directly from the image itself, and I am trying to convert this byte[] into a Bitmap object.
I am using the code:
var provider = new MultipartMemoryStreamProvider();
var multipart = Request.Content.ReadAsMultipartAsync(provider).ContinueWith(t => {
foreach (var item in provider.Contents) {
var filename = item.Headers.ContentDisposition.FileName.Trim('\"');
var buffer = item.ReadAsByteArrayAsync();
MemoryStream mss = new MemoryStream(buffer.Result);
Bitmap bmpImage = (Bitmap)Image.FromStream(mss);
//bmpImage.GetPixel(10,10) returns ARGB values of 255,255,255,255
}
});
However, when I call bmpImage.GetPixel(10,10), the ARGB values are 255,255,255,255. This makes no sense to me. Does anyone have any ideas why this conversion could be causing a loss of my pixel information?
The above code is wrapped in the ApiController Post() method:
public async Task<IHttpActionResult> Post()
Replacing:
var buffer = item.ReadAsByteArrayAsync();
MemoryStream mss = new MemoryStream(buffer.Result);
Bitmap bmpImage = (Bitmap)Image.FromStream(mss);
with:
Stream stream = item.ReadAsStreamAsync().Result;
Bitmap bmpImage = (Bitmap)Image.FromStream(stream);
did the trick. I don't initally see the why the second works and the first doesn't, but the ReadAsStreamAsync() call works and the ReadAsByteArrayAsync() doesn't.
Related
I am trying to compress image(usually around 5-30) quality / size with ImageSharp.Web() library, and I cant really understand how can I do that or what I am missing here.
Can I reuse the same memory stream / IFormFile object to save the mutated image? Or do I need to create a new Image from current image object?
To work with a memory Stream do I also need to use specific JpegDecoder() ?
Not sure if this line is correct item.SaveAsJpeg(memoryStream);.
Maybe someone can help me out with the logic or any tips or tricks would be really helpful. Thanks!
Simple code example:
private byte[] ConvertImageToByteArray(IFormFile inputImage)
{
byte[] result = null;
// filestream
using (var fileStream = inputImage.OpenReadStream()) // IFormFile inputImage
// memory stream
using (var memoryStream = new MemoryStream())
{
fileStream.CopyTo(memoryStream);
memoryStream.Position = 0; // The position needs to be reset.
var before = memoryStream.Length;
using (var item = Image.Load(memoryStream)) // do I need to use here JpegDecoder?
{
var beforeMutations = item.Size();
// dummy resize options
int width = 50;
int height = 100;
IResampler sampler = KnownResamplers.Lanczos3;
bool compand = true;
ResizeMode mode = ResizeMode.Stretch;
// init resize object
var resizeOptions = new ResizeOptions
{
Size = new Size(width, height),
Sampler = sampler,
Compand = compand,
Mode = mode
};
// mutate image
item.Mutate(x => x
.Resize(resizeOptions)
.Rotate(35));
var afterMutations = item.Size();
// try to save mutated image back to memory stream / overwrite
// this is not overwriting memory stream
item.SaveAsJpeg(memoryStream);
// prepare result to byte[]
result = memoryStream.ToArray();
}
var after = fileStream.Length; // kind of not needed.
}
I know this post is a bit old, and I'm sure that you have fixed your issue, but hopefully, it'll help some else out in the future.
Can I reuse the same memory stream / IFormFile object to save the mutated image? Or do I need to create a new Image from current image object?
You have two streams going on here, you can use one for the image from IFormFile and you can manipulate everything here, and then use your MemoryStream to save to
To work with a memory Stream do I also need to use specific JpegDecoder()?
You can save your image to the Memory Stream with .SaveAsJpeg(memoryStream)
Not sure if this line is correct item.SaveAsJpeg(memoryStream);.
You are on the right track
Maybe someone can help me out with the logic or any tips or tricks would be really helpful. Thanks!
Here is my rewrite based on what you have: Hope this helps. I'm sure there are some things that can be simplified, I tried to keep it close to OPs format
private byte[] ConvertImageToByteArray(IFormFile inputImage)
{
byte[] result = null;
// memory stream
using (var memoryStream = new MemoryStream())
// filestream
using (var image = Image.Load(inputImage.OpenReadStream())) // IFormFile inputImage
{
//var before = memoryStream.Length; Removed this, assuming you are using for debugging?
var beforeMutations = image.Size();
// dummy resize options
int width = 50;
int height = 100;
IResampler sampler = KnownResamplers.Lanczos3;
bool compand = true;
ResizeMode mode = ResizeMode.Stretch;
// init resize object
var resizeOptions = new ResizeOptions
{
Size = new Size(width, height),
Sampler = sampler,
Compand = compand,
Mode = mode
};
// mutate image
image.Mutate(x => x
.Resize(resizeOptions)
.Rotate(35));
var afterMutations = image.Size();
//Encode here for quality
var encoder = new JpegEncoder()
{
Quality = 30 //Use variable to set between 5-30 based on your requirements
};
//This saves to the memoryStream with encoder
image.Save(memoryStream, encoder);
memoryStream.Position = 0; // The position needs to be reset.
// prepare result to byte[]
result = memoryStream.ToArray();
var after = memoryStream.Length; // kind of not needed.
}
}
I have a base64 image and i have to convert it into Image. I am doing this using this code:
public static Image ConvertBase64StringToImage(string imageBase64String)
{
var imageBytes = Convert.FromBase64String(imageBase64String);
var imageStream = new MemoryStream(imageBytes, 0, imageBytes.Length);
imageStream.Write(imageBytes, 0, imageBytes.Length);
var image = Image.FromStream(imageStream, true);
return image;
}
Then i have to convert this Image into base64 again. Im using this code:
public static string ConvertImageToBase64String(Image image)
{
var imageStream = new MemoryStream();
image.Save(imageStream, ImageFormat.Png);
imageStream.Position = 0;
var imageBytes = imageStream.ToArray();
return Convert.ToBase64String(imageBytes);
}
After converting the original base64Image to image and again to base64, it loses quality.The Original base64 image is 1676 in length and after conversion it has 1660 in length.
I need the same image after conversion because i have to compare it. Any ideas how to do it without losing quality?
According to this page although PNG files are lossless, you can specify how much file compression to use when storing. IMO, as long as the Image comes out the same (you can compare them using some sort of MD5 tool), it doesn't matter if the size of the file is different when you save it, as the actual image is still the same as the original.
This is how to convert and compare your images, if the result from CompareImages is zero, it means that they are equal or very similar.
static void Main(string[] args)
{
Image img = new Bitmap("Koala.jpg");
string img64Bit = ConvertImageToBase64String(img);
Image newImg = ConvertBase64StringToImage(img64Bit);
newImg.Save("KoalaCopy.jpg");
Console.WriteLine(CompareImages(img, newImg));
Console.ReadLine();
}
public static string ConvertImageToBase64String(Image image)
{
using (MemoryStream ms = new MemoryStream())
{
image.Save(ms, image.RawFormat);
return Convert.ToBase64String(ms.ToArray());
}
}
public static Image ConvertBase64StringToImage(string image64Bit)
{
byte[] imageBytes = Convert.FromBase64String(image64Bit);
return new Bitmap(new MemoryStream(imageBytes));
}
public static int CompareImages(Image i1, Image i2)
{
string img1 = ConvertImageToBase64String(i1);
string img2 = ConvertImageToBase64String(i2);
return String.Compare(img1, img2);
}
I have an image that's loaded in XAML using a converter. Rather than load this image again, I want to take that image and find the dominant colour to be able to use for other graphics on the page. So far I have this:
var himage = (BitmapImage)image_home.Source;
using (var stream = await himage.OpenReadAsync()) //**can't open himage this way**
{
//Create a decoder for the image
var decoder = await BitmapDecoder.CreateAsync(stream);
//Create a transform to get a 1x1 image
var myTransform = new BitmapTransform { ScaledHeight = 1, ScaledWidth = 1 };
//Get the pixel provider
var pixels = await decoder.GetPixelDataAsync(
BitmapPixelFormat.Rgba8,
BitmapAlphaMode.Ignore,
myTransform,
ExifOrientationMode.IgnoreExifOrientation,
ColorManagementMode.DoNotColorManage);
//Get the bytes of the 1x1 scaled image
var bytes = pixels.DetachPixelData();
//read the color
var myDominantColor = Color.FromArgb(255, bytes[0], bytes[1], bytes[2]);
}
Obviously I can't open the BitmapImage himage using OpenReadAsync, what do I need to do there to be able to achieve this?
BitmapDecoder requires RandomAccessStream object to create a new instance. BitmapImage may not be directly extract as RandomAccessStream unless you know the original source. According to your comment, you are binding image Uri to the image control, so you could know the original source and you can get the RandomAccessStream from the BitmapImage's UriSource property by RandomAccessStreamReference class, you don't need load the Image again. Code as follows:
var himage = (BitmapImage)image_home.Source;
RandomAccessStreamReference random = RandomAccessStreamReference.CreateFromUri(himage.UriSource);
using (IRandomAccessStream stream = await random.OpenReadAsync())
{
//Create a decoder for the image
var decoder = await BitmapDecoder.CreateAsync(stream);
...
//read the color
var myDominantColor = Color.FromArgb(255, bytes[0], bytes[1], bytes[2]);
}
I have the following code to convert image to base64:
private void btnSave_Click(object sender, RoutedEventArgs e)
{
StreamResourceInfo sri = null;
Uri uri = new Uri("Checked.png", UriKind.Relative);
sri = Application.GetResourceStream(uri);
BitmapImage bitmap = new BitmapImage();
bitmap.SetSource(sri.Stream);
WriteableBitmap wb = new WriteableBitmap(bitmap);
MemoryStream ms = new MemoryStream();
wb.SaveJpeg(ms, bitmap.PixelWidth, bitmap.PixelHeight, 0, 100);
byte[] imageBytes = ms.ToArray();
base64 = System.Convert.ToBase64String(imageBytes);
}
And the following code to get Bitmap image form base 64:
public static BitmapImage base64image(string base64string)
{
byte[] fileBytes = Convert.FromBase64String(base64string);
using (MemoryStream ms = new MemoryStream(fileBytes, 0, fileBytes.Length))
{
ms.Write(fileBytes, 0, fileBytes.Length);
BitmapImage bitmapImage = new BitmapImage();
bitmapImage.SetSource(ms);
return bitmapImage;
}
}
So when i convert and deconvert it is blank.
I know that deconverter works, because, when i give him exact string:
string base64="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";
Which is my Checked.png converted in online converter. It decompreses perfectly.
And this is my base64, which i get by converting:
"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"
My problem is that string which i get as base64 from my code - is incorrect *What i did wrong?*
What about trying:
public static BitmapImage base64image(string base64string)
{
byte[] fileBytes = Convert.FromBase64String(base64string);
using (MemoryStream ms = new MemoryStream(fileBytes))
{
Image streamImage = Image.FromStream(ms);
context.Response.ContentType = "image/jpeg";
streamImage.Save(context.Response.OutputStream, ImageFormat.Jpeg);
return streamImage;
}
}
I agree with Alexei that your code for reading the image in does look a little strange. I've recently written some code for a similar task that I was doing which might point you in the right direction:
string fileContent = null;
/* Check the file actually has some content to display to the user */
if (uploadFile != null && uploadFile.ContentLength > 0)
{
byte[] fileBytes = new byte[uploadFile.ContentLength];
int byteCount = uploadFile.InputStream.Read(fileBytes, 0, (int)uploadFile.ContentLength);
if (byteCount > 0)
{
fileContent = CreateBase64Image(fileBytes);
}
}
private string CreateBase64Image(byte[] fileBytes)
{
Image streamImage;
/* Ensure we've streamed the document out correctly before we commit to the conversion */
using (MemoryStream ms = new MemoryStream(fileBytes))
{
/* Create a new image, saved as a scaled version of the original */
streamImage = ScaleImage(Image.FromStream(ms));
}
using (MemoryStream ms = new MemoryStream())
{
/* Convert this image back to a base64 string */
streamImage.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
return Convert.ToBase64String(ms.ToArray());
}
}
not an answer: more of a long comment ... OP states that decoding code works perfectly fine, also it looks suspicios. Also code assumed to be verified to work on PNG images, but saving code explicitly produces valid JPG with SaveJpeg call...
Your code that creates stream for reading looks strange - you create stream over existing byte array, than write the same bytes into that stream, and that pass that stream without seeking back to 0 to some method.
Potential fix (assuming BitampImage can accept JPG stream):
don't call Write at all as stream already have the bytes you want
set ms.Position = 0 after writing to the stream.
Note: I'm not sure if it is OK to dispose stream that is a source for BitmapImage, you may need to remove using too.
I'm trying to convert a byte array to a bitmap but it always shows me:
System.ArgumentException: Parameter is not valid.
My code is as follows:
I'm passing the bytes through a webservice with:
string DecodedString = string.Empty;
DecodedString = System.Text.Encoding.GetEncoding(1251).GetString(bytes);
sResult = sResult + "<Photo>" +XmlConvert.EncodeName(DecodedString) + "</Photo>";
and in my webPage:
byte[] bytes = (Byte[])System.Text.Encoding.GetEncoding(1251).GetBytes(XmlConvert.DecodeName(xDocument.SelectSingleNode("Response/Images/Photo").InnerText));
System.IO.MemoryStream ms = new System.IO.MemoryStream(bytes);
System.Drawing.Bitmap b = new System.Drawing.Bitmap(ms);//(System.Drawing.Image.FromStream(ms));
Try passing the string as a Base64:
string DecodedString = string.Empty;
DecodedString = System.Convert.ToBase64String(bytes)
sResult = sResult + "<Photo>" +XmlConvert.EncodeName(DecodedString) + "</Photo>";
...
byte[] bytes = System.Convert.FromBase64String(xDocument.SelectSingleNode("Response/Images/Photo").InnerText);
System.IO.MemoryStream ms = new System.IO.MemoryStream(bytes);
System.Drawing.Bitmap b = System.Drawing.Image.FromStream(ms);
You also won't need to use XmlConvert to encode/decode the string.
I did it, with the help of all of you, here is my page code
byte[] bytes = System.Convert.FromBase64String(xDocument.SelectSingleNode("Response/Images/Photo").InnerText);
System.IO.MemoryStream ms = new System.IO.MemoryStream(bytes);
System.Drawing.Bitmap b = new System.Drawing.Bitmap(ms); //(Bitmap)System.Drawing.Image.FromStream(ms);
System.Drawing.Imaging.FrameDimension frameDim;
frameDim = new System.Drawing.Imaging.FrameDimension(b.FrameDimensionsList[0]);
int NumberOfFrames = b.GetFrameCount(frameDim);
string[] paths = new string[NumberOfFrames];
for (int i = 0; i < NumberOfFrames; i++)
{
b.SelectActiveFrame(frameDim, i);
System.Drawing.Bitmap bmp = new System.Drawing.Bitmap(b);
paths[i] = imagePathfile.Remove(imagePathfile.Length - 4, 4) + i.ToString() + ".gif";
bmp.Save(paths[i], System.Drawing.Imaging.ImageFormat.Gif);
//bmp.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Gif);
bmp.Dispose();
}
Image1.Src = paths[0];
//Check if there's more than 1 image cause its a TIFF
if (paths.Length>1)
{
Image2.Src = paths[1];
}
I had a similar problem recently, but using Silverlight. I ended up needing to create a Custom HTTP Handler in order to pass the byte[] that defined the image back as a stream.
See http://www.dotnetcurry.com/ShowArticle.aspx?ID=220
Edit: This allows you to avoid worrying about XML encoding, and passes the image back in Binary form... YMMV
According to MSDN:
ArgumentException - The stream does not have a valid image format
I believe your problem is in the original byte[] array you are passing to the web service.
According to one of your comments, you did:
System.IO.FileStream fs = new System.IO.FileStream(sPath, System.IO.FileMode.Open, System.IO.FileAccess.Read);
int streamLength = Convert.ToInt32(fs.Length);
bytes = new byte[streamLength];
fs.Read(bytes, 0, streamLength);
fs.Read returns the number of bytes that have been read into the byte array; it doesn't always read the entire file!
Try using the StreamFile method from http://www.dotnetspider.com/resources/4515-convert-file-into-byte-array.aspx. (First result of Google search)
Try this:
byte[] bytes = System.Convert.FromBase64String(xDocument.SelectSingleNode("Response/Images/Photo").InnerText);
System.Drawing.ImageConverter imageConverter = new System.Drawing.ImageConverter();
Image image = imageConverter.ConvertFrom(bytes) as Image;
System.Drawing.Bitmap b = new System.Drawing.BitMap(image);
EDIT
Take a look at this:
Transfer any files on Web services by c#
actually i had been meet this problem, In my case, when i use IE browser, it is ok but when use another browser it always have the same error.
"Parameter is not valid exception is always happening in the same line of code:
System.Drawing.Image.FromStream(ms));"
So i think it seems this issue depend on browser and type of image (JPEG,JPEG2000).
Here is some code I used converting bytes to an image for a unit test:
protected override Image LoadImage()
{
//get a temp image from bytes, instead of loading from disk
//data:image/gif;base64,
byte[] bytes = Convert.FromBase64String("R0lGODlhAQABAIAAAAAAAAAAACH5BAAAAAAALAAAAAABAAEAAAICTAEAOw==");
Image image;
using (MemoryStream ms = new MemoryStream(bytes))
{
image = Image.FromStream(ms);
}
return image;
}
To my understanding, the image can not be shown because the format of the image's bytes is not correct. Every image format has its own head or something.