Symptom:

When you save or upload a image in buffer as a JPEG file, you may receive the following error message:



Cause:

You are saving a Black&White image as a JPEG file. JPEG standard defines that only 256 gray-scaled image and 24 bit RGB image can be compressed as JPEG format.

Resolution:

Please make sure the pixel type of the image in buffer is Gray or RGB. You can set the value of pixel type by using the PixelType property.

Code:

function btnScan_onclick()
{
   frmScan.DynamicWebTwain1.SelectSource();
   frmScan.DynamicWebTwain1.OpenSource(); 
   frmScan.DynamicWebTwain1.PixelType = 2; //RGB
   
   frmScan.DynamicWebTwain1.AcquireImage();
}

Reference:

PixelType  HTTPUploadThroughPost  SaveAsJPEG