Batch Export?

[Teemac]

I'm working on converting .blp files to .jpg and some of them appear as just lines of the whole image with blank areas of white in between when viewing them on the browser and when I batch convert to jpg. However if I export the image to jpg it shows up correctly. Is there a way to do a batch export because I'm working on thousands of images and one by one export would be very painful. Or if you have another solution that would be great.

[xnview]

If you use batch convert, the ouput result is bad, and if you use 'save as' it's good?