Trying to bring out "true" colours as a human would see them. 1:1 crops of the same frame, no sharpening, no noise reduction, "natural" colour saturation, Daylight White Balance. Camera was not modded, but the location had high light pollution. Top row shows the frame converted from Raw using "Normal" conversion as is used for normal photography, i.e. with the gamma curves. Bottom row used "Linear" conversion but otherwise the same settings. Going from left to right, the second pair shows what happens when the toffee/chocolate skyfog is subtracted. Conclusion: the backdrop to the Trapezium is blue; perhaps even teal? As from OIII emission? The Linear-converted set allowed a full subtraction of the skyfog without tempering of the star colours, and does show wisps of red, most likely from strong Ha emissions. Note how noisy the DSLRs of 2003 were. This was the top DSLR of the day...