I'm trying to create a 32 BPP gray scale tiff using this code which I found on MSDN
BitmapSource image = BitmapSource.Create(
width,
height,
96,
96,
PixelFormats.Gray32Float,
null,
pixels,
stride);
FileStream stream = new FileStream("test file.tif", FileMode.Create);
TiffBitmapEncoder encoder = new TiffBitmapEncoder();
encoder.Compression = TiffCompressOption.None;
var bitmapFrame = BitmapFrame.Create(image);
encoder.Frames.Add(bitmapFrame);
encoder.Save(stream);
The file gets created and the image looks correct when I open it, but the file properties says that it is a 16 BPP (0-65536) image not a 32 bit floating point as specified by the Gray32Float parameter.
I've confirmed the file format is 16 BPP by looking at the file properties in windows explorer and by opening the file in ImageJ
I can create 32 BPP tiffs in Paint.Net and ImageJ, to confirm that format is supported.
Anyone know why the .Net TiffBitmapEncoder is creating the wrong type?
Under the hood, .Net uses the Windows Imaging Component (WIC). WIC supports reading of TIFFs in Gray32Float (GUID_WICPixelFormat32bppGrayFloat in WIC) but not writing. Take a look at the WIC Native Pixel Formats Overview. I had the same experience discovering the image was written as Gray16.
This is very frustrating. I've been attempting to writes some scientific data using Gray32Float, but I have not been successful.
Old question, but I tried, and almost made it, but still - doesn't work correctly:
What I have here is a solution which saves as 32bit, using TiffLib, but the value range is somehow not correct.
I save an image in float range of -0.5 to 3, and imageJ reads it as 32 bit, BUT the range is ~-1000K to ~3000K...
I tried using TiffLib adding the following functions:
public static void Write32BitTiff_(string path, int W, int H, float[] data, ref byte[] FileData, int numPage = 0)
{
var numBytes = sizeof(float);
var size = H * W * numBytes;
byte[] arr = null;
arr = new byte[size];
var ctr = 0;
byte[] floatVal;
for (int i = 0; i < size; i += numBytes)
{
try
{
float val = data[ctr++];
floatVal = BitConverter.GetBytes(val);
for (int j = 0; j < numBytes; j++)
arr[i + j] = floatVal[j];
}
catch (IndexOutOfRangeException)
{
break;
}
catch (Exception eee) { }
}
Tiff t = openTiff(path, W, H, numPage, numBytes * 8);
t.WriteRawStrip(0, arr, size);
t.Close();
t.Dispose();
}
Where "OpenTiff" looks like this:
private static Tiff openTiff(string path, int W, int H, int pageNum, int numBits, bool overrideFile = false)
{
Tiff t;
int numberOfPages;
if (!File.Exists(path) || overrideFile )
{
t = Tiff.Open(path, "w");
numberOfPages = 1;
}
else
{
var start = DateTime.Now;
t = Tiff.Open(path, "a");
numberOfPages = t.NumberOfDirectories() + 1; ;
numberOfPages = (pageNum > numberOfPages) ? pageNum : numberOfPages;
}
t.SetField(TiffTag.IMAGEWIDTH, W);
t.SetField(TiffTag.IMAGELENGTH, H);
const int NUM_CHANNELS = 1;//for RGB set 3. for ARGB set 4, not sure supported.
t.SetField(TiffTag.SAMPLESPERPIXEL, NUM_CHANNELS);
t.SetField(TiffTag.BITSPERSAMPLE, numBits);
t.SetField(TiffTag.PHOTOMETRIC, Photometric.MINISBLACK);
t.SetField(TiffTag.SUBFILETYPE, FileType.PAGE);
t.SetField(TiffTag.PAGENUMBER, pageNum, numberOfPages);
t.SetDirectory((short)pageNum);
}
So if this might help someone, or if someone could find the "bug" with it - this would be great!
I am trying to encode a recorded audio using Nspeex and then transfer it over internet and decode on the other end. I am doing all this in Windows Phone 7/8. To encode and decode I am using following code. But while decoding I am not getting the result back correctly which I can play again. Can anyone provide me with encoding and decoding code which runs on WP7/8 recorded audio:
private static Microphone mic = Microphone.Default;
private static byte[] EncodeSpeech(byte[] buf, int len)
{
BandMode mode = GetBandMode(mic.SampleRate);
SpeexEncoder encoder = new SpeexEncoder(mode);
// set encoding quality to lowest (which will generate the smallest size in the fastest time)
encoder.Quality = 1;
int inDataSize = len / 2;
// convert to short array
short[] data = new short[inDataSize];
int sampleIndex = 0;
for (int index = 0; index < len; index += 2, sampleIndex++)
{
data[sampleIndex] = BitConverter.ToInt16(buf, index);
}
// note: the number of samples per frame must be a multiple of encoder.FrameSize
inDataSize = inDataSize - inDataSize % encoder.FrameSize;
var encodedData = new byte[len];
int encodedBytes = encoder.Encode(data, 0, inDataSize, encodedData, 0, len);
if (encodedBytes != 0)
{
// each chunk is laid out as follows:
// | 4-byte total chunk size | 4-byte encoded buffer size | <encoded-bytes> |
byte[] inDataSizeBuf = BitConverter.GetBytes(inDataSize);
byte[] sizeBuf = BitConverter.GetBytes(encodedBytes + inDataSizeBuf.Length);
byte[] returnBuf = new byte[encodedBytes + sizeBuf.Length + inDataSizeBuf.Length];
sizeBuf.CopyTo(returnBuf, 0);
inDataSizeBuf.CopyTo(returnBuf, sizeBuf.Length);
Array.Copy(encodedData, 0, returnBuf, sizeBuf.Length + inDataSizeBuf.Length, encodedBytes);
return returnBuf;
}
else
return buf;
}
private byte[] DecodeSpeech(byte[] buf)
{
BandMode mode = GetBandMode(mic.SampleRate);
SpeexDecoder decoder = new SpeexDecoder(mode);
byte[] inDataSizeBuf = new byte[4];
byte[] sizeBuf = new byte[4];
byte[] encodedBuf = new byte[buf.Length - 8];
Array.Copy(buf, 0, sizeBuf, 0, 4);
Array.Copy(buf, 4, inDataSizeBuf, 0, 4);
Array.Copy(buf, 8, encodedBuf, 0, buf.Length - 8);
int inDataSize = BitConverter.ToInt32(inDataSizeBuf, 0);
int size = BitConverter.ToInt32(sizeBuf, 0);
short[] decodedBuf = new short[inDataSize];
int decodedSize = decoder.Decode(encodedBuf, 0, encodedBuf.Length, decodedBuf, 0, false);
byte[] returnBuf = new byte[inDataSize * 2];
for (int index = 0; index < decodedBuf.Length; index++)
{
byte[] temp = BitConverter.GetBytes(decodedBuf[index]);
Array.Copy(temp, 0, returnBuf, index * 2, 2);
}
return returnBuf;
}
private static BandMode GetBandMode(int sampleRate)
{
if (sampleRate <= 8000)
return BandMode.Narrow;
if (sampleRate <= 16000)
return BandMode.Wide;
return BandMode.UltraWide;
}
I think your problem may be that you are newing up a new SpeexEncoder every time you want to encode audio. You should try making that a member for your class and re-use it.
I looked at the code for Nspeex I noticed that SpeexEncoder uses NbEncoder for the narrow band. In that class it looks like it keeps a history of some previous audio data in order perform the encoding. This should mean that the output for different instances of encoders would not go together.
private static Microphone mic = Microphone.Default;
private static SpeexEncoder encoder = CreateEncoder();
private static SpeexEncoder CreateEncoder()
{
BandMode mode = GetBandMode(mic.SampleRate);
SpeexEncoder encoder = new SpeexEncoder(mode);
// set encoding quality to lowest (which will generate the smallest size in the fastest time)
encoder.Quality = 1;
return encoder;
}
private static byte[] EncodeSpeech(byte[] buf, int len)
{
int inDataSize = len / 2;
...
I try to compare 2 images. For this i use 2 PreentScreens doing one after another(it is idential). When I compare this screens using pixels comparing:
public static CompareResult Compare(Bitmap bmp1, Bitmap bmp2)
{
CompareResult cr = CompareResult.ciCompareOk;
if (bmp1.Size != bmp2.Size)
{
cr = CompareResult.ciSizeMismatch;
}
else
{
for (int x = 0; x < bmp1.Width
&& cr == CompareResult.ciCompareOk; x++)
{
for (int y = 0; y < bmp1.Height
&& cr == CompareResult.ciCompareOk; y++)
{
if (bmp1.GetPixel(x, y) != bmp2.GetPixel(x, y))
cr = CompareResult.ciPixelMismatch;
}
}
}
return cr;
}
I get correct result that says - compare are identical, but it take a lot of time and when I'm try to hash this Bitmaps and compare it values - I get wrong result. When I compare image with itself - everything OK. What can be wrong? Here is code for hash comparing:
public enum CompareResult
{
ciCompareOk,
ciPixelMismatch,
ciSizeMismatch
};
public static CompareResult Compare(Bitmap bmp1, Bitmap bmp2)
{
CompareResult cr = CompareResult.ciCompareOk;
//Test to see if we have the same size of image
if (bmp1.Size != bmp2.Size)
{
cr = CompareResult.ciSizeMismatch;
}
else
{
//Convert each image to a byte array
System.Drawing.ImageConverter ic =
new System.Drawing.ImageConverter();
byte[] btImage1 = new byte[1];
btImage1 = (byte[])ic.ConvertTo(bmp1, btImage1.GetType());
byte[] btImage2 = new byte[1];
btImage2 = (byte[])ic.ConvertTo(bmp2, btImage2.GetType());
//Compute a hash for each image
SHA256Managed shaM = new SHA256Managed();
byte[] hash1 = shaM.ComputeHash(btImage1);
byte[] hash2 = shaM.ComputeHash(btImage2);
//Compare the hash values
for (int i = 0; i < hash1.Length && i < hash2.Length
&& cr == CompareResult.ciCompareOk; i++)
{
if (hash1[i] != hash2[i])
cr = CompareResult.ciPixelMismatch;
}
}
return cr;
}
Possible duplicate of How to compare Image objects with C# .NET? which contains sample code.
Another useful link is this blog post by Dominic Green. The code is somewhat smaller and uses Base64 hashing instead of SHA256 hashing. This is significantly faster, but you should be aware that comparing images is not a light operation.
But returning to the question itself, how sure are you that both images are equal? Is it possible there might be a slight difference between the two images? Your mouse cursor moved, the clock display updated, ...
I have a problem to convert an byte array to double array using BitConverter.ToDouble().
Simply my program will select an image then convert the image to byte array.
Then it will convert the byte array to double array.
The problem that when I convert the byte array to the double I will get this error before the loop finish.
(Destination array is not long enough to copy all the items in the collection. Check array index and length.)
The error happen exactly at array.Length-7 position which is last seventh position before the last position on the array.
I need help to solve this problem and here is my code:
private Bitmap loadPic;
byte[] imageArray;
double[] dImageArray;
private void btnLoad_Click(object sender, EventArgs e)
{
try
{
OpenFileDialog open = new OpenFileDialog();
open.Filter = "Image Files(*.jpg; *.jpeg; *.gif; *.bmp)|*.jpg; *.jpeg; *.gif; *.bmp";
if (open.ShowDialog() == DialogResult.OK)
{
pictureBox1.Image = new Bitmap(open.FileName);
loadPic = new Bitmap(pictureBox1.Image);
}
}
catch
{
throw new ApplicationException("Failed loading image");
}
pictureBox1.SizeMode = PictureBoxSizeMode.StretchImage;
}
private void btnConvert_Click(object sender, EventArgs e)
{
imageArray = imageToByteArray(loadPic);
int index = imageArray.Length;
dImageArray = new double[index];
for (int i = 0; i < index; i++)
{
dImageArray[i] = BitConverter.ToDouble(imageArray,i);
}
}
public byte[] imageToByteArray(Image imageIn)
{
MemoryStream ms = new MemoryStream();
imageIn.Save(ms, ImageFormat.Gif);
return ms.ToArray();
}
BitConverter.ToDouble(byte[], int)
uses eight bytes to construct a 64-bit double, which explains your problem (once you get to the 7th to last element, there are no longer eight bytes left). I'm guessing this is not what you want to do, based on how you set up your loop.
I imagine you want something like:
for(int i = 0; i < index; i++)
{
dImageArray[i] = (double)imageArray[i];
}
Edit - or using LINQ, just for fun:
double[] dImageArray = imageArray.Select(i => (double)i).ToArray();
On the other hand...
If BitConverter is definitely what you want, then you'll need something like:
double[] dImageArray = new double[imageArray.Length / 8];
for (int i = 0; i < dImageArray.Length; i++)
{
dImageArray[i] = BitConverter.ToDouble(imageArray, i * 8);
}
Again, based on your code, I think the first solution is what you need.
class Program
{
static void Main(string[] args)
{
Program p = new Program();
p.Test();
}
private void Test()
{
Image i = Image.FromFile(#"C:\a.jpg");
Bitmap b = new Bitmap(i);
MemoryStream ms = new MemoryStream();
b.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
byte[] by = ms.ToArray();
double[] db = new double[(int)(Math.Ceiling((double)by.Length / 8))];
int startInterval = 1;
int interval = 8;
int k = 0;
byte[] bys = new byte[8];
int n = 1;
for (int m = startInterval; m <= interval && m<=by.Length; m++,n++)
{
bys[n-1] = by[m-1];
if (m == interval)
{
db[k] = BitConverter.ToDouble(bys, 0);
startInterval += 8;
interval += 8;
k++;
n = 0;
Array.Clear(bys, 0, bys.Length);
}
if (m == by.Length)
{
db[k] = BitConverter.ToDouble(bys, 0);
}
}
}
}
I think you need to back up a bit and explain what you are actually trying to do. Each BitConverter.ToDouble will convert 8 consecutive bytes into 1 double. If you start at the next position in the byte array, you are using 7 bytes that have already been used. Since each conversion will need 8 bytes, you will need to stop at Length - 7.
Anyway, you are going to end up inflating the size of the data by a factor of 8.
I think some explanation of what this is for might help you get some better answers.
Is there a cheap way to get the dimensions of an image (jpg, png, ...)? Preferably, I would like to achieve this using only the standard class library (because of hosting restrictions). I know that it should be relatively easy to read the image header and parse it myself, but it seems that something like this should be already there. Also, I’ve verified that the following piece of code reads the entire image (which I don’t want):
using System;
using System.Drawing;
namespace Test
{
class Program
{
static void Main(string[] args)
{
Image img = new Bitmap("test.png");
System.Console.WriteLine(img.Width + " x " + img.Height);
}
}
}
Your best bet as always is to find a well tested library. However, you said that is difficult, so here is some dodgy largely untested code that should work for a fair number of cases:
using System;
using System.Collections.Generic;
using System.Drawing;
using System.IO;
using System.Linq;
namespace ImageDimensions
{
public static class ImageHelper
{
const string errorMessage = "Could not recognize image format.";
private static Dictionary<byte[], Func<BinaryReader, Size>> imageFormatDecoders = new Dictionary<byte[], Func<BinaryReader, Size>>()
{
{ new byte[]{ 0x42, 0x4D }, DecodeBitmap},
{ new byte[]{ 0x47, 0x49, 0x46, 0x38, 0x37, 0x61 }, DecodeGif },
{ new byte[]{ 0x47, 0x49, 0x46, 0x38, 0x39, 0x61 }, DecodeGif },
{ new byte[]{ 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A }, DecodePng },
{ new byte[]{ 0xff, 0xd8 }, DecodeJfif },
};
/// <summary>
/// Gets the dimensions of an image.
/// </summary>
/// <param name="path">The path of the image to get the dimensions of.</param>
/// <returns>The dimensions of the specified image.</returns>
/// <exception cref="ArgumentException">The image was of an unrecognized format.</exception>
public static Size GetDimensions(string path)
{
using (BinaryReader binaryReader = new BinaryReader(File.OpenRead(path)))
{
try
{
return GetDimensions(binaryReader);
}
catch (ArgumentException e)
{
if (e.Message.StartsWith(errorMessage))
{
throw new ArgumentException(errorMessage, "path", e);
}
else
{
throw e;
}
}
}
}
/// <summary>
/// Gets the dimensions of an image.
/// </summary>
/// <param name="path">The path of the image to get the dimensions of.</param>
/// <returns>The dimensions of the specified image.</returns>
/// <exception cref="ArgumentException">The image was of an unrecognized format.</exception>
public static Size GetDimensions(BinaryReader binaryReader)
{
int maxMagicBytesLength = imageFormatDecoders.Keys.OrderByDescending(x => x.Length).First().Length;
byte[] magicBytes = new byte[maxMagicBytesLength];
for (int i = 0; i < maxMagicBytesLength; i += 1)
{
magicBytes[i] = binaryReader.ReadByte();
foreach(var kvPair in imageFormatDecoders)
{
if (magicBytes.StartsWith(kvPair.Key))
{
return kvPair.Value(binaryReader);
}
}
}
throw new ArgumentException(errorMessage, "binaryReader");
}
private static bool StartsWith(this byte[] thisBytes, byte[] thatBytes)
{
for(int i = 0; i < thatBytes.Length; i+= 1)
{
if (thisBytes[i] != thatBytes[i])
{
return false;
}
}
return true;
}
private static short ReadLittleEndianInt16(this BinaryReader binaryReader)
{
byte[] bytes = new byte[sizeof(short)];
for (int i = 0; i < sizeof(short); i += 1)
{
bytes[sizeof(short) - 1 - i] = binaryReader.ReadByte();
}
return BitConverter.ToInt16(bytes, 0);
}
private static int ReadLittleEndianInt32(this BinaryReader binaryReader)
{
byte[] bytes = new byte[sizeof(int)];
for (int i = 0; i < sizeof(int); i += 1)
{
bytes[sizeof(int) - 1 - i] = binaryReader.ReadByte();
}
return BitConverter.ToInt32(bytes, 0);
}
private static Size DecodeBitmap(BinaryReader binaryReader)
{
binaryReader.ReadBytes(16);
int width = binaryReader.ReadInt32();
int height = binaryReader.ReadInt32();
return new Size(width, height);
}
private static Size DecodeGif(BinaryReader binaryReader)
{
int width = binaryReader.ReadInt16();
int height = binaryReader.ReadInt16();
return new Size(width, height);
}
private static Size DecodePng(BinaryReader binaryReader)
{
binaryReader.ReadBytes(8);
int width = binaryReader.ReadLittleEndianInt32();
int height = binaryReader.ReadLittleEndianInt32();
return new Size(width, height);
}
private static Size DecodeJfif(BinaryReader binaryReader)
{
while (binaryReader.ReadByte() == 0xff)
{
byte marker = binaryReader.ReadByte();
short chunkLength = binaryReader.ReadLittleEndianInt16();
if (marker == 0xc0)
{
binaryReader.ReadByte();
int height = binaryReader.ReadLittleEndianInt16();
int width = binaryReader.ReadLittleEndianInt16();
return new Size(width, height);
}
binaryReader.ReadBytes(chunkLength - 2);
}
throw new ArgumentException(errorMessage);
}
}
}
Hopefully the code is fairly obvious. To add a new file format you add it to imageFormatDecoders with the key being an array of the "magic bits" which appear at the beginning of every file of the given format and the value being a function which extracts the size from the stream. Most formats are simple enough, the only real stinker is jpeg.
using (FileStream file = new FileStream(this.ImageFileName, FileMode.Open, FileAccess.Read))
{
using (Image tif = Image.FromStream(stream: file,
useEmbeddedColorManagement: false,
validateImageData: false))
{
float width = tif.PhysicalDimension.Width;
float height = tif.PhysicalDimension.Height;
float hresolution = tif.HorizontalResolution;
float vresolution = tif.VerticalResolution;
}
}
the validateImageData set to false prevents GDI+ from performing costly analysis of the image data, thus severely decreasing load time. This question sheds more light on the subject.
Have you tried using the WPF Imaging classes? System.Windows.Media.Imaging.BitmapDecoder, etc.?
I believe some effort was into making sure those codecs only read a subset of the file in order to determine header information. It's worth a check.
I was looking for something similar a few months earlier. I wanted to read the type, version, height and width of a GIF image but couldn’t find anything useful online.
Fortunately in case of GIF, all the required information was in the first 10 bytes:
Type: Bytes 0-2
Version: Bytes 3-5
Height: Bytes 6-7
Width: Bytes 8-9
PNG are slightly more complex (width and height are 4-bytes each):
Width: Bytes 16-19
Height: Bytes 20-23
As mentioned above, wotsit is a good site for detailed specs on image and data formats though the PNG specs at pnglib are much more detailed. However, I think the Wikipedia entry on PNG and GIF formats is the best place to start.
Here’s my original code for checking GIFs, I have also slapped together something for PNGs:
using System;
using System.IO;
using System.Text;
public class ImageSizeTest
{
public static void Main()
{
byte[] bytes = new byte[10];
string gifFile = #"D:\Personal\Images&Pics\iProduct.gif";
using (FileStream fs = File.OpenRead(gifFile))
{
fs.Read(bytes, 0, 10); // type (3 bytes), version (3 bytes), width (2 bytes), height (2 bytes)
}
displayGifInfo(bytes);
string pngFile = #"D:\Personal\Images&Pics\WaveletsGamma.png";
using (FileStream fs = File.OpenRead(pngFile))
{
fs.Seek(16, SeekOrigin.Begin); // jump to the 16th byte where width and height information is stored
fs.Read(bytes, 0, 8); // width (4 bytes), height (4 bytes)
}
displayPngInfo(bytes);
}
public static void displayGifInfo(byte[] bytes)
{
string type = Encoding.ASCII.GetString(bytes, 0, 3);
string version = Encoding.ASCII.GetString(bytes, 3, 3);
int width = bytes[6] | bytes[7] << 8; // byte 6 and 7 contain the width but in network byte order so byte 7 has to be left-shifted 8 places and bit-masked to byte 6
int height = bytes[8] | bytes[9] << 8; // same for height
Console.WriteLine("GIF\nType: {0}\nVersion: {1}\nWidth: {2}\nHeight: {3}\n", type, version, width, height);
}
public static void displayPngInfo(byte[] bytes)
{
int width = 0, height = 0;
for (int i = 0; i <= 3; i++)
{
width = bytes[i] | width << 8;
height = bytes[i + 4] | height << 8;
}
Console.WriteLine("PNG\nWidth: {0}\nHeight: {1}\n", width, height);
}
}
Based on the answers so far and some additional searching, it seems that in the .NET 2 class library there is no functionality for it. So I decided to write my own. Here is a very rough version of it. At the moment, I needed it only for JPG’s. So it completes the answer posted by Abbas.
There is no error checking or any other verification, but I currently need it for a limited task, and it can be eventually easily added. I tested it on some number of images, and it usually does not read more that 6K from an image. I guess it depends on the amount of the EXIF data.
using System;
using System.IO;
namespace Test
{
class Program
{
static bool GetJpegDimension(
string fileName,
out int width,
out int height)
{
width = height = 0;
bool found = false;
bool eof = false;
FileStream stream = new FileStream(
fileName,
FileMode.Open,
FileAccess.Read);
BinaryReader reader = new BinaryReader(stream);
while (!found || eof)
{
// read 0xFF and the type
reader.ReadByte();
byte type = reader.ReadByte();
// get length
int len = 0;
switch (type)
{
// start and end of the image
case 0xD8:
case 0xD9:
len = 0;
break;
// restart interval
case 0xDD:
len = 2;
break;
// the next two bytes is the length
default:
int lenHi = reader.ReadByte();
int lenLo = reader.ReadByte();
len = (lenHi << 8 | lenLo) - 2;
break;
}
// EOF?
if (type == 0xD9)
eof = true;
// process the data
if (len > 0)
{
// read the data
byte[] data = reader.ReadBytes(len);
// this is what we are looking for
if (type == 0xC0)
{
width = data[1] << 8 | data[2];
height = data[3] << 8 | data[4];
found = true;
}
}
}
reader.Close();
stream.Close();
return found;
}
static void Main(string[] args)
{
foreach (string file in Directory.GetFiles(args[0]))
{
int w, h;
GetJpegDimension(file, out w, out h);
System.Console.WriteLine(file + ": " + w + " x " + h);
}
}
}
}
Updated ICR's answer to support progressive jPegs & WebP as well :)
internal static class ImageHelper
{
const string errorMessage = "Could not recognise image format.";
private static Dictionary<byte[], Func<BinaryReader, Size>> imageFormatDecoders = new Dictionary<byte[], Func<BinaryReader, Size>>()
{
{ new byte[] { 0x42, 0x4D }, DecodeBitmap },
{ new byte[] { 0x47, 0x49, 0x46, 0x38, 0x37, 0x61 }, DecodeGif },
{ new byte[] { 0x47, 0x49, 0x46, 0x38, 0x39, 0x61 }, DecodeGif },
{ new byte[] { 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A }, DecodePng },
{ new byte[] { 0xff, 0xd8 }, DecodeJfif },
{ new byte[] { 0x52, 0x49, 0x46, 0x46 }, DecodeWebP },
};
/// <summary>
/// Gets the dimensions of an image.
/// </summary>
/// <param name="path">The path of the image to get the dimensions of.</param>
/// <returns>The dimensions of the specified image.</returns>
/// <exception cref="ArgumentException">The image was of an unrecognised format.</exception>
public static Size GetDimensions(BinaryReader binaryReader)
{
int maxMagicBytesLength = imageFormatDecoders.Keys.OrderByDescending(x => x.Length).First().Length;
byte[] magicBytes = new byte[maxMagicBytesLength];
for(int i = 0; i < maxMagicBytesLength; i += 1)
{
magicBytes[i] = binaryReader.ReadByte();
foreach(var kvPair in imageFormatDecoders)
{
if(StartsWith(magicBytes, kvPair.Key))
{
return kvPair.Value(binaryReader);
}
}
}
throw new ArgumentException(errorMessage, "binaryReader");
}
private static bool StartsWith(byte[] thisBytes, byte[] thatBytes)
{
for(int i = 0; i < thatBytes.Length; i += 1)
{
if(thisBytes[i] != thatBytes[i])
{
return false;
}
}
return true;
}
private static short ReadLittleEndianInt16(BinaryReader binaryReader)
{
byte[] bytes = new byte[sizeof(short)];
for(int i = 0; i < sizeof(short); i += 1)
{
bytes[sizeof(short) - 1 - i] = binaryReader.ReadByte();
}
return BitConverter.ToInt16(bytes, 0);
}
private static int ReadLittleEndianInt32(BinaryReader binaryReader)
{
byte[] bytes = new byte[sizeof(int)];
for(int i = 0; i < sizeof(int); i += 1)
{
bytes[sizeof(int) - 1 - i] = binaryReader.ReadByte();
}
return BitConverter.ToInt32(bytes, 0);
}
private static Size DecodeBitmap(BinaryReader binaryReader)
{
binaryReader.ReadBytes(16);
int width = binaryReader.ReadInt32();
int height = binaryReader.ReadInt32();
return new Size(width, height);
}
private static Size DecodeGif(BinaryReader binaryReader)
{
int width = binaryReader.ReadInt16();
int height = binaryReader.ReadInt16();
return new Size(width, height);
}
private static Size DecodePng(BinaryReader binaryReader)
{
binaryReader.ReadBytes(8);
int width = ReadLittleEndianInt32(binaryReader);
int height = ReadLittleEndianInt32(binaryReader);
return new Size(width, height);
}
private static Size DecodeJfif(BinaryReader binaryReader)
{
while(binaryReader.ReadByte() == 0xff)
{
byte marker = binaryReader.ReadByte();
short chunkLength = ReadLittleEndianInt16(binaryReader);
if(marker == 0xc0 || marker == 0xc2) // c2: progressive
{
binaryReader.ReadByte();
int height = ReadLittleEndianInt16(binaryReader);
int width = ReadLittleEndianInt16(binaryReader);
return new Size(width, height);
}
if(chunkLength < 0)
{
ushort uchunkLength = (ushort)chunkLength;
binaryReader.ReadBytes(uchunkLength - 2);
}
else
{
binaryReader.ReadBytes(chunkLength - 2);
}
}
throw new ArgumentException(errorMessage);
}
private static Size DecodeWebP(BinaryReader binaryReader)
{
binaryReader.ReadUInt32(); // Size
binaryReader.ReadBytes(15); // WEBP, VP8 + more
binaryReader.ReadBytes(3); // SYNC
var width = binaryReader.ReadUInt16() & 0b00_11111111111111; // 14 bits width
var height = binaryReader.ReadUInt16() & 0b00_11111111111111; // 14 bits height
return new Size(width, height);
}
}
I did this for PNG file
var buff = new byte[32];
using (var d = File.OpenRead(file))
{
d.Read(buff, 0, 32);
}
const int wOff = 16;
const int hOff = 20;
var Widht =BitConverter.ToInt32(new[] {buff[wOff + 3], buff[wOff + 2], buff[wOff + 1], buff[wOff + 0],},0);
var Height =BitConverter.ToInt32(new[] {buff[hOff + 3], buff[hOff + 2], buff[hOff + 1], buff[hOff + 0],},0);
Yes, you can absolutely do this and the code depends on the file format. I work for an imaging vendor (Atalasoft), and our product provides a GetImageInfo() for every codec that does the minimum to find out dimensions and some other easy to get data.
If you want to roll your own, I suggest starting with wotsit.org, which has detailed specs for pretty much all image formats and you will see how to identify the file and also where information in it can be found.
If you are comfortable working with C, then the free jpeglib can be used to get this information too. I would bet that you can do this with .NET libraries, but I don't know how.
It's going to depend on the file format. Usually they will state it up in the early bytes of the file. And, usually, a good image-reading implementation will take that into account. I can't point you to one for .NET though.