It works for me:
Dim rawData As Byte() = File.ReadAllBytes("D:\Test Data\BigImage.jpg")
Dim base64 As String = Convert.ToBase64String(rawData)
Console.WriteLine("{0}:{1}", rawData.Length, base64.Length)
Gives me:
3489676:4652904
Which is an input image data file twice the size of the ones giving you problems. OK, I'm not reading my data from Oracle - it's coming from a file so I know it's a "large image" - but once it's in an array it's just data as far as the system is concerned.
So I'd start by looking at your code and working out exactly what you are doing, before deciding it's the conversion to base64 that is causing your problem.
"can you try to implement your converted image in img tag ?"
Works fine for me!
byte[] rawData = File.ReadAllBytes(@"D:\Test Data\BigImage.jpg");
string base64 = Convert.ToBase64String(rawData);
Response.Write(string.Format("<img src=\"data:image/jpg;base64,{0}\">", base64));
Dim rawData As Byte() = File.ReadAllBytes("D:\Test Data\BigImage.jpg")
Dim base64 As String = Convert.ToBase64String(rawData)
Response.Write(String.Format("<img src=""data:image/jpg;base64,{0}"">", base64))
Admittedly, my browser doesn't look pretty with a dirty great 3880x4997 image slapped into it, but...it works.