We have PDF File which has size from 700MB to 1GB. This is because it contains the high resolution images which is required for processing means resolution cant be reduced .
Can any one has an implementation of viewing such large Files
You'd be better off creating a version for whatever processing you are doing and one for online viewing.
I think it is good idea to reduce resolution of images and create another version for online view
The customer will need the bandwidth to download 1GB of data, and the memory requirements will be huge; possibly such large amounts will be blocked by some browsers. I don't think the document services API is what you need if you will not compromise, and nor will any similar competitor, since you have created your own limitations. You may want a server-side renderer - but PDF is really not ideal for this. Rendering portions of huge data sets on demand is a specialist task - but is used by mapping apps and the like. No doubt specially prepared data in multiple resolutions, or a vector derivable map, is used. Otherwise, your spec pushes beyond today's reasonable limits. Maybe in 10 years.
Customer has such a large file today it's not 10 years beyond requrement
You can make a file, and decide you have a requirement, but it does not make it possible. My "10 years" estimate is a rough estimate of when computer power and internet speeds might have reached a point to entertain such an idea. Meanwhile, I think you have the advice you need to start a new and different approach.