Filtered x-ray diodes, sensitive in different spectral regions, are used to measure the emission spectrum of laser-driven hohlraums at the Omega laser facility in Rochester, NY. Here we present two new methods to reconstruct the emission spectra from the response of the x-ray diodes and compare them to the method currently used to extract a spectrum and a temperature in the hohlraum. We also use simulated spectra to characterize the different methods with respect to uncertainty, emission temperature, and the ability to reconstruct the input spectrum as closely as possible.