Obviousness

A patent for a claimed invention cannot be obtained if the differences between the claimed invention and the prior art would have been obvious to a person having ordinary skill in the art at the time the invention was made. This "non-obviousness" standard is outlined in 35 U.S.C. § 103. When evaluating obviousness, an examiner may combine multiple prior art references to demonstrate that the claimed invention would have been obvious. The motivation to combine references can come from various factors, including combining elements according to known methods to yield predictable results, or simply substituting one known equivalent for another to obtain predictable results.

US patent 9054728B2, titled "Data compression systems and methods," claims systems and methods for data compression using both content-independent and content-dependent data compression and decompression. The patent lists one prior art document: US09/210,491, which is identified as patent/US6195024B1/en in the Google Patents information. This appears to be a misidentification in the source data, as US09/210,491 is the application number for US patent 6195024B1. Therefore, for the purpose of this analysis, the primary prior art reference will be considered US patent 6195024B1.

US patent 6195024B1, "Content dependent data compression system and method," describes a data compression system that includes a data pre-compressor for identifying the data type of an input stream and generating a data type identification signal, and a data compressor that selects a data compression method from a preselected set of methods based on the identified data type to achieve the best compression ratio (see "FIG. 1" and associated description in US9054728B2, which identifies it as prior art). This system is explicitly called out as "prior art" in the description of US9054728B2.

Let's consider the independent claims of US9054728B2:

Claim 1 claims a method for compressing data, comprising:

• receiving a data block;
• analyzing the data block to recognize a characteristic selected from the group consisting of a data type, data structure, data block format, file substructure, and file types, and generating a recognition signal;
• performing content dependent data compression on the data block using a first plurality of encoders, if the characteristic is recognized, to provide a plurality of first encoded data blocks;
• performing content independent data compression on the data block using a second plurality of encoders, if the characteristic is not recognized, to provide a plurality of second encoded data blocks;
• determining a plurality of compression ratios for the first encoded data blocks and for the second encoded data blocks;
• selecting an encoded data block from the first encoded data blocks or the second encoded data blocks based on the determined compression ratios; and
• outputting the selected encoded data block with a compression type descriptor.

Obviousness Analysis of Claim 1:

US patent 6195024B1 (the explicitly cited prior art in US9054728B2) clearly teaches a content-dependent data compression system. It describes a "data pre-compressor 2" that "accepts an uncompressed data stream, identifies the data type of the input stream, and generates a data type identification signal" [Description of US9054728B2, referring to FIG. 1 of the prior art]. It also describes a "data compressor 3" that "selects a data compression method from a preselected set of methods to compress the input data stream, with the intention of producing the best available compression ratio for that particular data type" [Description of US9054728B2, referring to FIG. 1 of the prior art]. This directly covers the steps of:

• receiving a data block;
• analyzing the data block to recognize a characteristic... and generating a recognition signal;
• performing content dependent data compression... if the characteristic is recognized...;
• determining a plurality of compression ratios...;
• selecting an encoded data block... based on the determined compression ratios; and
• outputting the selected encoded data block with a compression type descriptor.

The distinguishing feature of Claim 1 of US9054728B2 over US patent 6195024B1 is the inclusion of "performing content independent data compression on the data block using a second plurality of encoders, if the characteristic is not recognized."

The problem identified in the background of US9054728B2 with prior art content-dependent systems is the "need to unambiguously identify various data types" and that it "may be difficult and/or impractical to predict which data encoding technique yields the highest compression ratio" for a known data type or mix of data types [Description of US9054728B2, "One such limitation..."]. Another problem cited is "negative compression may occur when certain data compression techniques act upon many types of highly compressed data" [Description of US9054728B2, "a further problem"].

A person having ordinary skill in the art (PHOSITA) in data compression, aware of the limitations of content-dependent systems (e.g., failing to recognize a data type or achieving poor compression), would be motivated to include a fallback mechanism. The concept of applying multiple encoders and selecting the best result, regardless of data type recognition, is a known technique for optimizing compression (as exemplified by the "content independent data compression system" discussed in US9054728B2 as its own invention in FIGS. 2-8).

Therefore, a PHOSITA, seeking to overcome the limitations of content-dependent compression when data types are not recognized or are poorly compressed, would find it obvious to combine the content-dependent compression taught by US patent 6195024B1 with a content-independent compression approach. The content-independent approach would act as a contingency plan for cases where content recognition fails or yields suboptimal results. The motivation would be to improve the robustness and overall compression performance of the system across a wider range of data types and conditions. The content-independent compression system would simply apply various compression algorithms to the data block and select the best one, as described in the content independent embodiments of US9054728B2 (e.g., FIG. 2, steps 306-326). This combination would yield predictable results, as both content-dependent and content-independent compression techniques are known in the art, and their sequential application (where content-independent serves as a fallback) is a logical extension to address the limitations of each individually.

Therefore, Claim 1 would be obvious over US patent 6195024B1 in combination with the general knowledge in the art regarding the use of multiple compression algorithms to find the best compression ratio, especially when content-specific recognition is not feasible or effective.

Further claims that build upon Claim 1 by adding specific details, such as the use of desirability factors (Claim 5), timers (Claim 7), or cascaded encoders (Claim 9), would also be obvious if those individual features were known in the prior art or would be obvious modifications for a PHOSITA. For example, the concept of desirability factors and timers are described as part of the "present invention" in US9054728B2 but address general issues in data compression (e.g., user preferences for compression characteristics, or real-time processing constraints), which a PHOSITA would seek to address with known solutions. The use of cascaded encoders to "increase the data compression ratio" is also a general principle in data compression [Description of US9054728B2, discussing FIG. 9].