Clean up or remove background on images

I am looking for someone to clean up the background on approximately 2850 images. Half are 300x300px and half are 150x150px I am hoping someone could use ImageMagick or something similar to do this as a batch. I had someone create these images using a cad program and when the image was captured there were artifacts left in the background. You can see the images I am talking about on this website: [login to view URL] I will provide you with a directory where all the images are located. I would prefer you to make the background transparent. I want to keep the image quality the same with the same filename and PNG format. ## Deliverables I am looking for someone to clean up the background on approximately 2850 images. Half are 300x300px and half are 150x150px I am hoping someone could use ImageMagick or something similar to do this as a batch. I had someone create these images using a cad program and when the image was captured there were artifacts left in the background. You can see the images I am talking about on this website: [login to view URL] I will provide you with a directory where all the images are located. I would prefer you to make the background transparent. But...I will accept bids that they will use a solid white background. I want to keep the image quality the same with the same filename and PNG format. The deliverables are the 2850 images with the background removed.