Deserialization .json to Bitmap image c#

Question

I have a bitmap image, which I converted to a JSON file using:

string json = new System.Web.Script.Serialization.JavaScriptSerializer().Serialize(Bitmap image);

Content of .json file:

{  
   "Tag":null,
   "PhysicalDimension":{  
      "IsEmpty":false,
      "Width":376,
      "Height":221
   },
   "Size":{  
      "IsEmpty":false,
      "Width":376,
      "Height":221
   },
   "Width":376,
   "Height":221,
   "HorizontalResolution":96,
   "VerticalResolution":96,
   "Flags":2,
   "RawFormat":{  
      "Guid":"b96b3caa-0728-11d3-9d7b-0000f81ef32e"
   },
   "PixelFormat":2498570,
   "Palette":{  
      "Flags":62,
      "Entries":[  

      ]
   },
   "FrameDimensionsList":[  
      "7462dc86-6180-4c7e-8e3f-ee7333a7a483"
   ],
   "PropertyIdList":[  

   ],
   "PropertyItems":[  

   ]
}

Now I tried to deserialize the file in this way:

Bitmap bm = new System.Web.Script.Serialization.JavaScriptSerializer().Deserialize<Bitmap>(json);

But got the error:

System.MissingMethodException: "For the" System.Bitmap "type, the constructor without parameters is not defined."

Is there another way to deserialize the file or how can I fix this code?

Thanks!

Possible duplicate of [Newtonsoft.Json deserializing base64 image fails](https://stackoverflow.com/questions/15510742/newtonsoft-json-deserializing-base64-image-fails) — BWA, Sep 27 '17 at 13:53
@MrsLSD do you realise that your JSON does not contain the actual image, only image properties. And on serialisation you will not be able to display the image again? — trailmax, Sep 27 '17 at 14:01
Maybe the question should be "How do I display a Bitmap in a picture box" — Magnus, Sep 27 '17 at 14:06
I should convert bitmap to json and load image again from file.json — MrsLSD, Sep 27 '17 at 14:07
@MrsLSD in that case Json serialisation is not suitable here. At least in the form you do it. Why do you need it in JSON anyway? — trailmax, Sep 27 '17 at 14:07
you are jsonizing the properties of the Bitmap type not the bitmap itself. — gsharp, Sep 27 '17 at 14:10
Unfortunately, yes, I need to do it some way. I have converted bmp to binary and XML and vise versa yet — MrsLSD, Sep 27 '17 at 14:10
Do you know why you are doing this, or somebody just tasked you to do it? — Magnus, Sep 27 '17 at 14:12
what do you want to achieve ? i mean do you need it to save it in a database or... ? — gsharp, Sep 27 '17 at 14:13
@MrsLSD Stop. Think about it. You have a binary object that can be saved as a file already. Then you need to show this file in a `pictureBox`. Just read that binary file again and show it. Why involve JSON and serialisation? — trailmax, Sep 27 '17 at 14:18
sorry but i don't get it. what is pictureBox a control ? winform ? wpf? web? — gsharp, Sep 27 '17 at 14:21

MBender · Answer 1 · 2017-09-27T14:18:43.637

The error of the message is... quite clear on this. If you look at the MSDN documentation for Bitmap, you'll find that it has no empty constructors defined. The JSON deserializer basically creates an new instance of a specified type (using the empty constructor) then fills out the properties. The Bitmap is a bit too complex for that to work. So... you need to work around that.

Bernard Vander Beken already showed you how to read a base64 string containin bitmap data. Here's how you can CREATE it from an existing bitmap:

ImageConverter converter = new ImageConverter();
var bitmapData = Convert.ToBase64String((byte[])converter.ConvertTo(bitmap, typeof(byte[])));

Note that bitmapData, in the example above, is a string which can easily be sent, stored, etc. (so no need to serialize this into JSON).

EDIT:

Please note that given the above, you need to update BOTH your serialization and deserialization code. I.e. to use the deserialization samples provided, you need to send / store a completely different JSON from the one you're currently working with... which won't be a JSON any more.

In fact, your current JSON file doesn't really contain an actual image; it only has some metadata about the image you originally used. So you definitely need to change the code responsible for serialization.

I would also modify the code for deserializing a bitmap ever so slightly (MemoryStream should, in theory, be disposed of properly and setting the position isn't required).

var bytes = Convert.FromBase64String(bitmapData);
Bitmap bitmap;
using (var ms = new MemoryStream(bytes))
  bitmap = new Bitmap(Bitmap.FromStream(ms));

@MrsLSD If what I wrote was the answer you sought, then yes, it would be nice if you marked this as the correct solution. ;) — MBender, Sep 27 '17 at 15:08

score 1 · Answer 2 · answered Sep 27 '17 at 13:55

Since Bitmap has no default constructor, it cannot be used out of the box for deserialization.

You can try to deserialize the JSON payload to a byte array, then pass it to Bitmap.FromStream via a MemoryStream.

string image = json;

byte[] byteBuffer = Convert.FromBase64String(image);
MemoryStream memoryStream = new MemoryStream(byteBuffer);
memoryStream.Position = 0;

return (Bitmap)Bitmap.FromStream(memoryStream);

Credits to http://ingsharksoft.blogspot.be/2013/07/solution-problem-serializedeserialize.html

I am not sure how an image is serialized. – Bernard Vander Beken Sep 27 '17 at 14:06 — Bernard Vander Beken, Sep 27 '17 at 14:06

Deserialization .json to Bitmap image c#

2 Answers2