The Arecibo message and both forms of the Dumas-Dutil message are constructed exclusively as pictograms. They are sequences of bits, grouped into "pages" which when viewed as black or white pixels, form low resolution images. These images express their meaning by way of pictograms. My question is why? OK, there are some concepts which require some form of diagramming, but for the first few pages of the Dumas-Dutil message, it's a set of equivalences. Couldn't they be more concisely and perhaps unambiguously expressed using an arbitrary binary code, rather than concocting an alphabet of glyphs to be low-res rasterized, laid out onto a binary canvas as the message, and then serialized into the form needed for transmission? What is the rationale behind the expression of the entire message in this form?
Assuming an alien technological civilization receives the signal, recognizes it to be artificial, and notices that it contains a stream of bits, are there not a whole host of further assumptions about what the message recipient would have to do, what choices they would have to make in order to interpret the message as intended? Can we be sure that they would even think to represent the bits in an array of pixels for further interpretation as images? What cues are built in to the message to facilitate this as the one and only thing to do at this step?
If the Dumas-Dutil message was presented to a human team of say, computer engineers with diverse specializations including image processing and cryptography, physicists, mathematicians, chemists, biologists, and astronomers, none of whom have any prior knowledge of the message, would they be able to correctly interpret it? Has this exercise ever been tried? This sort of thing was attempted with the Arecibo message with disappointing results.
Does the pictogram structure really improve the chances of successful interpretation, or do we have a requirement for the recipient to follow a sequence of steps, thinking like a human, each of which introduces the likelihood of an incorrect action and consequent failure to arrive at the intended result?