Im getting some images from a webpage at a specified url, i want to get their heights and widths. I'm using something like this:
Stream str = null;
HttpWebRequest wReq = (HttpWebRequest)WebRequest.Create(ImageUrl);
HttpWebResponse wRes = (HttpWebResponse)(wReq).GetResponse();
str = wRes.GetResponseStream();
var imageOrig = System.Drawing.Image.FromStream(str);
int height = imageOrig.Height;
int width = imageOrig.Width;
My main concern with this is that that the image file may actually be very large,
Is there anything I can do? ie specify to only get images if they are less than 1mb?
or is there a better alternative approach to getting the dimension of an image from a webpage?
thanks
Some (all?) image formats include the width and height property in the header of the file. You could just request enough bytes to be able to read the header and then parse them yourself. You can add a range header to your web request that will request only the first 50 bytes (50 is just an example, you'd probably need less) of the image file with:
wReq.AddRange(0, 50);
I suppose this will only work if you know that the formats you are working with include this data.
Edit: Looks like I misunderstood the AddRange method before. It's fixed now. I also went ahead and tested it out by getting the width and height of a png using this documentation.
static void Main(string[] args)
{
string imageUrl = "http://upload.wikimedia.org/wikipedia/commons/4/47/PNG_transparency_demonstration_1.png";
byte[] pngSignature = new byte[] { 137, 80, 78, 71, 13, 10, 26, 10 };
HttpWebRequest wReq = (HttpWebRequest)WebRequest.Create(imageUrl);
wReq.AddRange(0, 30);
WebResponse wRes = wReq.GetResponse();
byte[] buffer = new byte[30];
int width = 0;
int height = 0;
using (Stream stream = wRes.GetResponseStream())
{
stream.Read(buffer, 0, 30);
}
// Check for Png
// 8 byte - Signature
// 4 byte - Chunk length
// 4 byte - Chunk type - IDHR (Image Header)
// 4 byte - Width
// 4 byte - Height
// Other stuff we don't care about
if (buffer.Take(8).SequenceEqual(pngSignature))
{
var idhr = buffer.Skip(12);
width = BitConverter.ToInt32(idhr.Skip(4).Take(4).Reverse().ToArray(), 0);
height = BitConverter.ToInt32(idhr.Skip(8).Take(4).Reverse().ToArray(), 0);
}
// Check for Jpg
//else if (buffer.Take(?).SequenceEqual(jpgSignature))
//{
// // Do Jpg stuff
//}
// Check for Gif
//else if (etc...
Console.WriteLine("Width: " + width);
Console.WriteLine("Height: " + height);
Console.ReadKey();
}
You only need to download the header from a graphics file in order to find the picture size, see...
BMP: (only 26 bytes needed)
http://www.fileformat.info/format/bmp/corion.htm
JPG: (scan for "Star of Frame" marker)
http://wiki.tcl.tk/757
GIF: (10 bytes needed, i.e. first two words of Logical Screen Descriptor)
http://www.matthewflickinger.com/lab/whatsinagif/bits_and_bytes.asp
also, notice how you can read the first couple of bytes to find out what the file-type really is (don't rely on the extension of the filename. For example, a bmp could be named ".gif" by accident. Once you know the filetype you look at the spec to know what offset to read.
P.S. get yourself a hex editor, such as "Hex Editor XVI32", to see the file structure.
You can download XVI32 here: http://www.chmaas.handshake.de/delphi/freeware/xvi32/xvi32.htm
You may want to write a web service where given the input image name, provides the size as response.
Based on the resultant value, you can choose to download the image.
If you want something light weight than a web service, go for a HTTP Handler.
You could try using the FileInfo class like so to find the file size.
long fileSizeInKb = new FileInfo(fileName).Length / 1000;
if (fileSizeInKb < 1000)
{
// get image
}
The Length property returns the number of bytes in the current file.
Related
How can I specify the bit depth for the MagickImage.Read() function when reading binary files?
I have a 1024x1024 image represented by 8-bit grayscale values (total file length = 1024x1024 = 1048576 bytes). Using ImageMagick v.7.0.8-7 Q16 x64, I can convert the file using
magick.exe -depth 8 -size 1024x1024 -format Gray Gray:filepath.bin convertedfile.png
When I try to convert the file using Magick.NET Q16-AnyCPU v7.5.0.1,
public MagickImage ReadNewMagickImageFromBinary(string fileName){
MagickReadSettings settings = new MagickReadSettings();
settings.Width = 1024;
settings.Height = 1024; //if I use settings.Height = 512; , I'm OK.
settings.Format = MagickFormat.Gray;
//settings.Depth = 8; //didn't work
//settings.SetDefine(MagickFormat.Gray, "depth", "8"); //also didn't work
MagickImage newImage = new MagickImage();
newImage.Depth = 8; //this appears to be ignored once the Read function is called
newImage.Read(fileName, settings);
return newImage;
}
I get the error
Message: ImageMagick.MagickCorruptImageErrorException : unexpected
end-of-file '': No such file or directory #
error/gray.c/ReadGRAYImage/241
Indicating that the program has read past the end of the file. I've confirmed that Magick.NET is reverting to a 16-bit depth instead of the 8-bit depth I want. I can read the file using settings.Height = 512 instead of 1024, which gives me a squashed version of my grayscale image.
I learned from Memory consumption in Magick.NET that Magick.NET Q16 stores pixels in memory with 16-bit precision; I'm fine with that but it doesn't seem that should preclude 8-bit reading capabilities.
How do I force Magick.NET Q16 to read pixels in with an 8-bit depth?
I just published Magick.NET 7.6.0.0 that now has better API for reading raw pixels. You should change your code to this:
public MagickImage ReadNewMagickImageFromBinary(string fileName)
{
var width = 1024;
var height = 1024;
var storageType = StorageType.Char;
var mapping = "R";
var pixelStorageSettings = new PixelStorageSettings(width, height, storageType, mapping);
return new MagickImage(fileName, pixelStorageSettings);
}
One workaround is to use the Magick.NET Q8 version instead of Magick.NET Q16. I successfully read the file using the program Magick.NET Q8-AnyCPU 7.5.0.1.
I'm still hoping there's a solution that allows me to still use Magick.NET Q16, but this works for now.
My game takes a screenshot each game loop and stores it memory. The user can then press "print screen" to trigger "SaveScreenshot" (see code below) to store each screenshot as a PNG and also compile them into an AVI using SharpAvi. The saving of images works fine, and a ~2sec AVI is produced, but it doesn't show any video when played. It's just the placeholder VLC Player icon. I think this is very close to working, but I can't determine what's wrong. Please see my code below. If anyone has any ideas, I'd be very appreciative!
private Bitmap GrabScreenshot()
{
try
{
Bitmap bmp = new Bitmap(this.ClientSize.Width, this.ClientSize.Height);
System.Drawing.Imaging.BitmapData data =
bmp.LockBits(this.ClientRectangle, System.Drawing.Imaging.ImageLockMode.WriteOnly,
System.Drawing.Imaging.PixelFormat.Format24bppRgb);
GL.ReadPixels(0, 0, this.ClientSize.Width, this.ClientSize.Height, PixelFormat.Bgr, PixelType.UnsignedByte,
data.Scan0);
bmp.UnlockBits(data);
bmp.RotateFlip(RotateFlipType.RotateNoneFlipY);
return bmp;
} catch(Exception ex)
{
// occasionally getting GDI generic exception when rotating the image... skip that one.
return null;
}
}
private void SaveScreenshots()
{
var directory = "c:\\helioscreenshots\\";
var rootFileName = string.Format("{0}_", DateTime.UtcNow.Ticks);
var writer = new AviWriter(directory + rootFileName + ".avi")
{
FramesPerSecond = 30,
// Emitting AVI v1 index in addition to OpenDML index (AVI v2)
// improves compatibility with some software, including
// standard Windows programs like Media Player and File Explorer
EmitIndex1 = true
};
// returns IAviVideoStream
var aviStream = writer.AddVideoStream();
// set standard VGA resolution
aviStream.Width = this.ClientSize.Width;
aviStream.Height = this.ClientSize.Height;
// class SharpAvi.KnownFourCCs.Codecs contains FOURCCs for several well-known codecs
// Uncompressed is the default value, just set it for clarity
aviStream.Codec = KnownFourCCs.Codecs.Uncompressed;
// Uncompressed format requires to also specify bits per pixel
aviStream.BitsPerPixel = BitsPerPixel.Bpp32;
var index = 0;
while (this.Screenshots.Count > 0)
{
Bitmap screenshot = this.Screenshots.Dequeue();
var screenshotBytes = ImageToBytes(screenshot);
// write data to a frame
aviStream.WriteFrame(true, // is key frame? (many codecs use concept of key frames, for others - all frames are keys)
screenshotBytes, // array with frame data
0, // starting index in the array
screenshotBytes.Length); // length of the data
// save it!
// NOTE: compared jpeg, gif, and png. PNG had smallest file size.
index++;
screenshot.Save(directory + rootFileName + index + ".png", System.Drawing.Imaging.ImageFormat.Png);
}
// save the AVI!
writer.Close();
}
public static byte[] ImageToBytes(Image img)
{
using (var stream = new MemoryStream())
{
img.Save(stream, System.Drawing.Imaging.ImageFormat.Png);
return stream.ToArray();
}
}
From what I see, you're providing the byte-array in png-encoding, yet the stream is configured as KnownFourCCs.Codecs.Uncompressed.
Furthermore, from the manual:
AVI expects uncompressed data in format of standard Windows DIB, that is bottom-up bitmap of the specified bit-depth. For each frame, put its data in byte array and call IAviVideoStream.WriteFrame()
Next, all encoders expect input image data in specific format. It's BGR32 top-down - 32 bits per pixel, blue byte first, alpha byte not used, top line goes first. This is the format you can often get from existing images. [...] So, you simply pass an uncompressed top-down BGR32
I would retrieve the byte-array directly from the Bitmap using LockBits and Marshal.Copy as described in the manual.
I am uploading jpeg images as fast as i can to a web service (it is the requirement I have been given).
I am using async call to the web service and I calling it within a timer.
I am trying to optimise as much as possible and tend to use an old laptop for testing. On a normal/reasonable build PC all is OK. On the laptop I get high RAM usage.
I know I will get a higher RAM usage using that old laptop but I want to know the lowest spec PC the app will work on.
As you can see in the code below I am converting the jpeg image into a byte array and then I upload the byte array.
If I can reduce/compress/zip the bye array then I am hoping this will be 1 of the ways of improving memory usage.
I know jpegs are already compressed but if I compare the current byte array with the previous byre array then uploading the difference between this byte arrays I could perhaps compress it even more on the basis that some of the byte values will be zero.
If I used a video encoder (which would do the trick) I would not be real time as much I would like.
Is there an optimum way of comparing 2 byte arrays and outputting to a 3rd byte array? I have looked around but could not find an answer that I liked.
This is my code on the client:
bool _uploaded = true;
private void tmrLiveFeed_Tick(object sender, EventArgs e)
{
try
{
if (_uploaded)
{
_uploaded = false;
_live.StreamerAsync(Shared.Alias, imageToByteArray((Bitmap)_frame.Clone()), Guid.NewGuid().ToString()); //web service being called here
}
}
catch (Exception _ex)
{
//do some thing but probably time out error here
}
}
//web service has finished the client invoke
void _live_StreamerCompleted(object sender, AsyncCompletedEventArgs e)
{
_uploaded = true; //we are now saying we start to upload the next byte array
}
private wsLive.Live _live = new wsLive.Live(); //web service
private byte[] imageToByteArray(Image imageIn)
{
MemoryStream ms = new MemoryStream();
imageIn.Save(ms,System.Drawing.Imaging.ImageFormat.Jpeg); //convert image to best image compression
imageIn.Dispose();
return ms.ToArray();
}
thanks...
As C.Evenhuis said - JPEG files are compressed, and changing even few pixels results in complettly differrent file. So - comparing resulting JPEG files is useless.
BUT you can compare your Image objects - quick search results in finding this:
unsafe Bitmap PixelDiff(Bitmap a, Bitmap b)
{
Bitmap output = new Bitmap(a.Width, a.Height, PixelFormat.Format32bppArgb);
Rectangle rect = new Rectangle(Point.Empty, a.Size);
using (var aData = a.LockBitsDisposable(rect, ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb))
using (var bData = b.LockBitsDisposable(rect, ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb))
using (var outputData = output.LockBitsDisposable(rect, ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb))
{
byte* aPtr = (byte*)aData.Scan0;
byte* bPtr = (byte*)bData.Scan0;
byte* outputPtr = (byte*)outputData.Scan0;
int len = aData.Stride * aData.Height;
for (int i = 0; i < len; i++)
{
// For alpha use the average of both images (otherwise pixels with the same alpha won't be visible)
if ((i + 1) % 4 == 0)
*outputPtr = (byte)((*aPtr + *bPtr) / 2);
else
*outputPtr = (byte)~(*aPtr ^ *bPtr);
outputPtr++;
aPtr++;
bPtr++;
}
}
return output;
}
If your goal is to find out whether two byte arrays contain exactly the same data, you can create an MD5 hash and compare these as others have suggested. However in your question you mention you want to upload the difference which means the result of the comparison must be more than a simple yes/no.
As JPEGs are already compressed, the smallest change to the image could lead to a large difference in the binary data. I don't think any two JPEGs contain binary data similar enough to easily compare.
For BMP files you may find that changing a single pixel affects only one or a few bytes, and more importantly, the data for the pixel at a certain offset in the image is located at the same position in both binary files (given that both images are of equal size and color depth). So for BMPs the difference in binary data directly relates to the difference in the images.
In short, I don't think obtaining the binary difference between JPEG files will improve the size of the data to be sent.
When decoding an image within a PDF as FlateDecode via iTextSharp the image is distorted and I can't seem to figure out why.
The recognized bpp is Format1bppIndexed. If I modify the PixelFormat to Format4bppIndexed the image is recognizable to some degree (shrunk, coloring is off but readable) and is duplicated 4 times in a horizontal manner. If I adjust the pixel format to Format8bppIndexed it is also recognizable to some degree and is duplicated 8 times in a horizontal manner.
The image below is after a Format1bppIndexed pixel format approach. Unfortunately I am unable to show the others due to security constraints.
The code is seen below which is essentially the single solution I have come across littered around both SO and the web.
int xrefIdx = ((PRIndirectReference)obj).Number;
PdfObject pdfObj = doc.GetPdfObject(xrefIdx);
PdfStream str = (PdfStream)(pdfObj);
byte[] bytes = PdfReader.GetStreamBytesRaw((PRStream)str);
string filter = ((PdfArray)tg.Get(PdfName.FILTER))[0].ToString();
string width = tg.Get(PdfName.WIDTH).ToString();
string height = tg.Get(PdfName.HEIGHT).ToString();
string bpp = tg.Get(PdfName.BITSPERCOMPONENT).ToString();
if (filter == "/FlateDecode")
{
bytes = PdfReader.FlateDecode(bytes, true);
System.Drawing.Imaging.PixelFormat pixelFormat;
switch (int.Parse(bpp))
{
case 1:
pixelFormat = System.Drawing.Imaging.PixelFormat.Format1bppIndexed;
break;
case 8:
pixelFormat = System.Drawing.Imaging.PixelFormat.Format8bppIndexed;
break;
case 24:
pixelFormat = System.Drawing.Imaging.PixelFormat.Format24bppRgb;
break;
default:
throw new Exception("Unknown pixel format " + bpp);
}
var bmp = new System.Drawing.Bitmap(Int32.Parse(width), Int32.Parse(height), pixelFormat);
System.Drawing.Imaging.BitmapData bmd = bmp.LockBits(new System.Drawing.Rectangle(0, 0, Int32.Parse(width),
Int32.Parse(height)), System.Drawing.Imaging.ImageLockMode.WriteOnly, pixelFormat);
Marshal.Copy(bytes, 0, bmd.Scan0, bytes.Length);
bmp.UnlockBits(bmd);
bmp.Save(#"C:\temp\my_flate_picture-" + DateTime.Now.Ticks.ToString() + ".png", ImageFormat.Png);
}
What do I need to do to so that my image extraction works as desired when dealing with FlateDecode?
NOTE: I do not want to use another library to extract the images. I am looking for a solution leveraging ONLY iTextSharp and the .NET FW. If a solution exists via Java (iText) and is easily portable to .NET FW bits that would suffice as well.
UPDATE: The ImageMask property is set to true, which would imply that there is no color space and is therefore implicitly black and white. With the bpp coming in at 1, the PixelFormat should be Format1bppIndexed which as mentioned earlier, produces the embedded image seen above.
UPDATE: To get the image size I extracted it out using Acrobat X Pro and the image size for this particular example was listed as 2403x3005. When extracting via iTextSharp the size was listed as 2544x3300. I modified the image size within the debugger to mirror 2403x3005 however upon calling Marshal.Copy(bytes, 0, bmd.Scan0, bytes.Length); I get an exception raised.
Attempted to read or write protected memory. This is often an
indication that other memory is corrupt.
My assumption is that this is due to the modification of the size and thus no longer corresponding to the byte data that is being used.
UPDATE: Per Jimmy's recommendation, I verified that calling PdfReader.GetStreamBytes returns a byte[] length equal to widthheight/8 since GetStreamBytes should be calling FlateDecode. Manually calling FlateDecode and calling PdfReader.GetStreamBytes both produced a byte[] length of 1049401, while the widthheight/8 is 2544*3300/8 or 1049400, so there is a difference of 1. Not sure if this would be the root cause or not, an off by one; however I am not sure how to resolve if that is indeed the case.
UPDATE: In trying the approach mentioned by kuujinbo I am met with an IndexOutOfRangeException when I attempt to call renderInfo.GetImage(); within the RenderImage listener. The fact that the width*height/8 as stated earlier is off by 1 in comparison to the byte[] length when calling FlateDecode makes me think these are all one in the same; however a solution still eludes me.
at System.util.zlib.Adler32.adler32(Int64 adler, Byte[] buf, Int32 index, Int32 len)
at System.util.zlib.ZStream.read_buf(Byte[] buf, Int32 start, Int32 size)
at System.util.zlib.Deflate.fill_window()
at System.util.zlib.Deflate.deflate_slow(Int32 flush)
at System.util.zlib.Deflate.deflate(ZStream strm, Int32 flush)
at System.util.zlib.ZStream.deflate(Int32 flush)
at System.util.zlib.ZDeflaterOutputStream.Write(Byte[] b, Int32 off, Int32 len)
at iTextSharp.text.pdf.codec.PngWriter.WriteData(Byte[] data, Int32 stride)
at iTextSharp.text.pdf.parser.PdfImageObject.DecodeImageBytes()
at iTextSharp.text.pdf.parser.PdfImageObject..ctor(PdfDictionary dictionary, Byte[] samples)
at iTextSharp.text.pdf.parser.PdfImageObject..ctor(PRStream stream)
at iTextSharp.text.pdf.parser.ImageRenderInfo.PrepareImageObject()
at iTextSharp.text.pdf.parser.ImageRenderInfo.GetImage()
at cyos.infrastructure.Core.MyImageRenderListener.RenderImage(ImageRenderInfo renderInfo)
UPDATE: Trying varying the varying methods listed here in my original solution as well as the solution posed by kuujinbo with a different page in the PDF produces imagery; however the issues always surface when the the filter type is /FlateDecode and no image is produced for that given instance.
Try copy your data row by row, maybe it will solve the problem.
int w = imgObj.GetAsNumber(PdfName.WIDTH).IntValue;
int h = imgObj.GetAsNumber(PdfName.HEIGHT).IntValue;
int bpp = imgObj.GetAsNumber(PdfName.BITSPERCOMPONENT).IntValue;
var pixelFormat = PixelFormat.Format1bppIndexed;
byte[] rawBytes = PdfReader.GetStreamBytesRaw((PRStream)imgObj);
byte[] decodedBytes = PdfReader.FlateDecode(rawBytes);
byte[] streamBytes = PdfReader.DecodePredictor(decodedBytes, imgObj.GetAsDict(PdfName.DECODEPARMS));
// byte[] streamBytes = PdfReader.GetStreamBytes((PRStream)imgObj); // same result as above 3 lines of code.
using (Bitmap bmp = new Bitmap(w, h, pixelFormat))
{
var bmpData = bmp.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.WriteOnly, pixelFormat);
int length = (int)Math.Ceiling(w * bpp / 8.0);
for (int i = 0; i < h; i++)
{
int offset = i * length;
int scanOffset = i * bmpData.Stride;
Marshal.Copy(streamBytes, offset, new IntPtr(bmpData.Scan0.ToInt32() + scanOffset), length);
}
bmp.UnlockBits(bmpData);
bmp.Save(fileName);
}
If you're able to use the latest version (5.1.3), the API to extract FlateDecode and other image types has been simplified using the iTextSharp.text.pdf.parser namespace. Basically you use a PdfReaderContentParser to help you parse the PDF document, then you implement the IRenderListener interface specifically (in this case) to deal with images. Here's a working example HTTP handler:
<%# WebHandler Language="C#" Class="bmpExtract" %>
using System;
using System.Collections.Generic;
using System.IO;
using System.Web;
using iTextSharp.text;
using iTextSharp.text.pdf;
using iTextSharp.text.pdf.parser;
public class bmpExtract : IHttpHandler {
public void ProcessRequest (HttpContext context) {
HttpServerUtility Server = context.Server;
HttpResponse Response = context.Response;
PdfReader reader = new PdfReader(Server.MapPath("./bmp.pdf"));
PdfReaderContentParser parser = new PdfReaderContentParser(reader);
MyImageRenderListener listener = new MyImageRenderListener();
for (int i = 1; i <= reader.NumberOfPages; i++) {
parser.ProcessContent(i, listener);
}
for (int i = 0; i < listener.Images.Count; ++i) {
string path = Server.MapPath("./" + listener.ImageNames[i]);
using (FileStream fs = new FileStream(
path, FileMode.Create, FileAccess.Write
))
{
fs.Write(listener.Images[i], 0, listener.Images[i].Length);
}
}
}
public bool IsReusable { get { return false; } }
public class MyImageRenderListener : IRenderListener {
public void RenderText(TextRenderInfo renderInfo) { }
public void BeginTextBlock() { }
public void EndTextBlock() { }
public List<byte[]> Images = new List<byte[]>();
public List<string> ImageNames = new List<string>();
public void RenderImage(ImageRenderInfo renderInfo) {
PdfImageObject image = null;
try {
image = renderInfo.GetImage();
if (image == null) return;
ImageNames.Add(string.Format(
"Image{0}.{1}", renderInfo.GetRef().Number, image.GetFileType()
));
using (MemoryStream ms = new MemoryStream(image.GetImageAsBytes())) {
Images.Add(ms.ToArray());
}
}
catch (IOException ie) {
/*
* pass-through; image type not supported by iText[Sharp]; e.g. jbig2
*/
}
}
}
}
The iText[Sharp] development team is still working on the implementation, so I can't say for sure if it will work in your case. But it does work on this simple example PDF. (used above and with a couple of other PDFs I tried with bitmap images)
EDIT: I've been experimenting with the new API too and made a mistake in the original code example above. Should have initialized the PdfImageObject to null outside the try..catch block. Correction made above.
Also, when I use the above code on an unsupported image type, (e.g. jbig2) I get a different Exception - "The color depth XX is not supported", where "XX" is a number. And iTextSharp does support FlateDecode in all the examples I've tried. (but that's not helping you in this case, I know)
Is the PDF produced by third-party software? (non-Adobe) From what I've read in the book, some third-party vendors produce PDFs that aren't completely up to spec, and iText[Sharp] can't deal with some of these PDFs, while Adobe products can. IIRC I've seen cases specific to some PDFs generated by Crystal Reports on the iText mailing list that caused problems, here's one thread.
Is there any way you can generate a test PDF with the software you're using with some non-sensitive FlateDecode image(s)? Then maybe someone here could help a little better.
How to read a tiff file's dimension (width and height) and resolution (horizontal and vertical) without first loading it into memory by using code like the following. It is too slow for big files and I don't need to manipulate them.
Image tif = Image.FromFile(#"C:\large_size.tif");
float width = tif.PhysicalDimension.Width;
float height = tif.PhysicalDimension.Height;
float hresolution = tif.HorizontalResolution;
float vresolution = tif.VerticalResolution;
tif.Dispose();
Edit:
Those tiff files are Bilevel and have a dimension of 30x42 inch. The file sizes are about 1~2 MB. So the method above works Ok but slow.
Ran into this myself and found the solution (possibly here). Image.FromStream with validateImageData = false allows you access to the information you're looking for, without loading the whole file.
using(FileStream stream = new FileStream(#"C:\large_size.tif", FileMode.Open, FileAccess.Read))
{
using(Image tif = Image.FromStream(stream, false, false))
{
float width = tif.PhysicalDimension.Width;
float height = tif.PhysicalDimension.Height;
float hresolution = tif.HorizontalResolution;
float vresolution = tif.VerticalResolution;
}
}
As far as I know, all classes from System.Drawing namespace load image data immediately when image is open.
I think LibTiff.Net can help you to read image properties without loading image data. It's free and open-source (BSD license, suitable for commercial applications).
Here is a sample for your task (error checks are omitted for brevity):
using BitMiracle.LibTiff.Classic;
namespace ReadTiffDimensions
{
class Program
{
static void Main(string[] args)
{
using (Tiff image = Tiff.Open(args[0], "r"))
{
FieldValue[] value = image.GetField(TiffTag.IMAGEWIDTH);
int width = value[0].ToInt();
value = image.GetField(TiffTag.IMAGELENGTH);
int height = value[0].ToInt();
value = image.GetField(TiffTag.XRESOLUTION);
float dpiX = value[0].ToFloat();
value = image.GetField(TiffTag.YRESOLUTION);
float dpiY = value[0].ToFloat();
}
}
}
}
Disclaimer: I am one of the maintainers of the library.
Try this, it seems to be what you are looking for. Just skip everything after:
TIFFGetField(tif, TIFFTAG_IMAGEWIDTH, ref w); //your width
TIFFGetField(tif, TIFFTAG_IMAGELENGTH, ref h); //your height
TIFFGetField(tif, TIFFTAG_BITSPERSAMPLE, ref bits);
TIFFGetField(tif, TIFFTAG_SAMPLESPERPIXEL, ref samples);
Don't forget to close after you:
TIFFClose(tif);
The only way I can think of is reading the tiff binary header.
Here you can download the specification: http://partners.adobe.com/public/developer/tiff/index.html
Here is some code used to read Tiffs that you can use to learn:
http://www.koders.com/csharp/fidF6632006F25B8E5B3BCC62D13076B38D71847929.aspx?s=zoom
I created a library to read the tiff headers some time ago (with this two resources as base) but it was part of my employer code so I can't post my code here and I can say it is no really hard.
I Hope this helps.