A traditional X-ray screening image uses three pseudo-colors: high- and low-energy attenuation differences are crudely mapped to orange, green and blue — organics orange, inorganic mixtures green, metals blue. Three bands are still coarse: is that orange object a narcotic, an explosive, or a packet of food? Is that blue mass an iron block or high-grade precious metal? FjXray's multi-energy imaging answers by computing the effective atomic number (Zeff) for every pixel and coloring each material by grade. Machines of this kind are often called multi-color security scanners; FjXray offers 4-color and 7-color palettes.
As X-rays pass through an object, photons of different energies are absorbed to different degrees, and this difference is closely related to the material's effective atomic number (Zeff). Narcotics, explosives, food and plastics have a low Zeff; metals and precious metals a high one; ores and glass sit in between.
A multi-energy system collects several energy channels, estimates Zeff per pixel and maps it to a color. What you see is not what the object looks like, but which family of atoms it is made of. Dual energy provides the baseline discrimination; multiple channels refine it. FjXray machines offer 4-color / 7-color grading on a dual-energy architecture, plus a 3D mode switchable in one touch.
This directly serves X-ray ore sorting: sorting, raw-material spot checks and concentrate shipment inspection. An operator can tell “this is ore, not clutter” without opening the package and take a first look at grade distribution.
The demonstration places the material families screening cares about most into one scene: metals in blue, precious metals in magenta, inorganic mixtures in green, organics in orange, while suspected narcotics and explosives are highlighted in deep red. Each material keeps its own color, so operators can lock onto priority regions without opening every item.
Note: the coloring demonstrates the material-classification algorithm. In real workflows it assists interpretation; the final call is made by the operator using dual-view images and standard procedures.
| Material type | Zeff | 4-color | 7-color | Examples |
|---|---|---|---|---|
| Light organics | ≈7 | Orange | Orange | Light organic materials |
| Organics | 7–9 | Orange | Tangerine | Suspected narcotics, explosives |
| Light inorganics | 9–10 | Orange | Orange | Paper, Teflon, water |
| Inorganics | 10–19 | Green | Green | Glass and common inorganics |
| Heavy metals | 19–40 | Blue | Blue | Common metal parts |
| Dense metals | 40+ | Blue | Violet | Noble metals: silver, platinum, gold |
| Impenetrable | — | Red (Black) | Red (Black) | Lead, bismuth (hidden-threat flag) |
Seven colors is not simply “more colors”: it adds one band at each end of the scale — Tangerine gives light organics their own color, Violet gives precious metals their own.
How does a 7-color scanner differ from a 3-color scanner? A 3-color image has three bands; a 7-color scanner grades materials by Zeff into seven bands — Tangerine, Brown, Orange, Green, Blue, Violet, Red (Black).
6-color or 7-color? 6-color schemes usually extend the 3-color baseline. The 7-color grading adds a band at each end: light organics (Tangerine) and precious metals (Violet). Compare the band definition table, not the color count.
What ores can an X-ray ore sorting machine process? Minerals are separated by differences in Zeff and density; exact ore types, particle sizes and grades should be confirmed by sample testing.
What does each color mean? Tangerine = light organics, Brown = organics, Orange = light inorganics, Green = inorganics, Blue = heavy metals, Violet = dense metals (precious metals), Red (Black) = impenetrable.
Can color identify narcotics or explosives directly? No. Coloring highlights suspect regions; the operator makes the final call using dual-view images and standard procedures.
Behind a colored image is a shift from three coarse bands to multi-energy grading, and from density-based color to effective-atomic-number imaging. Want a picture like this for your own operation? Contact FjXray for a demo and sample testing.
Related models: FX6550D dual view · FX10080D dual view · FX5030C
