1. A method, in a data processing system comprising at least one processor and at least one memory, for generating alternative text descriptions for images in electronic documents, comprising: analyzing, by the data processing system, an original image embedded in an electronic document to generate a data pattern for the image; performing, by the data processing system, a matching operation to identify one or more similar images in other electronic documents from one or more sources of electronic documents based on the generated data pattern; extracting, by the data processing system, textual description information associated with the one or more similar images from data associated with the one or more similar images; generating, by the data processing system, an alternative text description for the original image based on the extracted textual description information associated with the one or more similar images; storing, by the data processing system, the alternative text description for the original image in association with the original image; generating a confidence level value for the alternative text description, wherein the confidence level value identifies a level of confidence that the alternative text description accurately describes content of the original image; and storing the confidence level value in association with the alternative text description, wherein the confidence level value is generated based on scoring each keyword in the alternative text description according to a frequency of occurrence of the keyword in textual description information associated with the one or more similar images and wherein the confidence level value is generated using the following relationship: 
 Confidence level value=( v /( v+m ))* R +( m /( v+m ))* C where R is an average score for the keywords in the alternative text description, v is a number of keywords in the alternative text description, m is a minimum number of keywords in the alternative text description required, and C is a mean confidence level value.
3. The method of claim 1 , wherein the confidence level value is generated based on a comparison of the alternative text description to an existing text description associated with the original image.