Blacked out text recovery

Ignoring some of the tangents in this thread, get your hands on the original, if it exists, and if it too is blacked out, look on the reverse side. If that data was typed in, or writen by hand, the paper has likely been embossed. Going over it with a soft-lead pencil might reveal the embossing enough to read the now mirror image. Try some of the stated Adjustments on this.

Otherwise, you might need the Photoshop-CSI edition.

Good luck,

Hunt

It is hardly improper or unethical to try to retrieve as much information as possible from a government-issued document.  If the government released the information then it is no longer withheld from the public. 

If the government tried to withhould information but didn't do so effectively, and the information were sent to an attorney that had requested it on behalf of a client, the attorney might be under a duty to inform the government of the error if discovered, and in some cases might be under an obligation not to disclose the inadvertently disclosed and potentially privileged information to the client.  But if the government publicly posts information or provides it to a private party requesting it for its own purposes, or gives it to reporters, and the information includes ineffectively redacted data, it's tough luck for the government.  The data is now public for anyone who wants to figure out how to retrieve it.  Sometimes it is text that's white-against-white.  Sometimes it's text that's there, but covered by a black or white layer.  Or whatever.  Once it's been publicly released, the cat's out of the bag.

Hint:  We own the government.  It doesn't own us. 

If the original is not available you can forget it.

It is obvious someone wants to prevent that information from being read.

Why don't you just look at the original document to learn what you were not likely entitled to know in the copy that you have?  Why don't the rest of us realize why information is redacted and that offering aid in this matter without knowing the whole story might be unethical and possibly illegal?

Another tool to try would be Image > Apply image. Also try the Trace Contour filter.

Is there a way to recover or bring out the hidden text?

A forensic X-Ray would be your best bet. Ask around, perhaps you can even find some radiologist in your area who would be willing to give this a spin.

Mylenium

It depends on many factors. The best way is the application of various light techniques to the original document. The further removed the document is from that scenario, the harder it gets. Photocopying, scanning, Photoshop...all contribute to the reduction in probability of recovering anything. There are cases in which it may be remotely possible, but honestly, this doesn’t look like one of them.