Welding is usually a monochrome course of, the place the guardian materials to be welded, the wire, the arc and torch are normally predominantly gray with little or no colour elements within the picture.
Some exceptions do exist nonetheless, comparable to GTAW / TIG or Plasma welding, the place some colour does exist, particularly of the welding torch.
In such circumstances, a colour digicam could also be a most well-liked option to picture the method to permit the operator the power to see some options that aren’t as straightforward to see with black and white imaging.
With a typical weld digicam system comparable to that supplied by Xiris, photos are generated by a colour digicam in a uncooked picture format that may have as much as 20 bits per pixel. These photos should then undergo a tone mapping course of to realize the very best quality of picture for show on displays which might be usually 8 bits per pixel.
This technique of tone mapping is important to enhancing colour photos in order that they are often of probably the most curiosity to the viewer. Each welder prefers to see that their very own particular options get enhanced by the tone mapping course of in order that they are often most seen and permit them to make higher choices about their course of. The way in which the tone mapping course of is ready up can outline which options in a weld picture are enhanced for the viewer. Sure options could be made extra seen by altering the imaging parameters of the tone mapping.
Options comparable to the vanguard of the soften pool, the seam width and place, the presence of the Warmth Affected Zone (HAZ) and the feel of the soften pool are all examples of options that may be enhanced by adjusting the tone mapping parameters.
Xiris has developed a strong colour imaging software program module as a part of its WeldStudio platform to permit the person to regulate the tone mapping parameters to make sure their options of curiosity are most seen. That is achieved by means of a sequence of steps:
- Firstly, the software program seems on the histogram data of every color channel. A digital colour picture is made up of three elements – Purple, Blue, and Inexperienced (or “RGB”). So, each pixel has its personal distinctive worth of Purple, Blue, and Inexperienced. The Min and Max of the histogram is measured for every RGB element and a “legitimate vary” of pixel depth values is “lower” from the enter vary.
- The tone mapping software program normalizes the colours for show such that the pixels on the backside of the vary are displayed as pure black, and people on the top quality are pure white, with intermediate values mapped accordingly. The Black and White values could be mechanically calculated by the software program, or they or they are often manually managed by the person. The calculation of the Black (backside lower) level and the White (high lower) level is influenced by the Darkish Degree and Saturation settings, respectively.
- The mapping of the legitimate vary to the output picture is linear by default. Nonetheless, it may be made non-linear utilizing Gamma or S-Curve
- Decreasing the Gamma will trigger extra element to be seen in the dead of night areas of the picture; growing it’ll trigger extra element to be seen within the shiny areas.
The S-Curve is a type of Look Up Desk (or “LUT”) that interprets how every enter RAW pixel shall be displayed as a part of the tone mapping course of.
Fig 2: An S-Curve with related controls used to vary Tone Mapping |
The S-Curves are generated utilizing an equation within the format:
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The place α and β are coefficient values that may be adjusted utilizing sliders to vary the form of the S-Curve. Within the case of colour photos, every R, G and B colour channel can have its personal curve. By adjusting the coefficients, the respective colour element could be made brighter or darker, serving to to reinforce the picture to spotlight sure options.
Lastly, the general picture Vibrancy could be adjusted to supply a rise within the depth of muted colours usually present in a welding course of, whereas leaving saturated colours (such because the weld arc or torch) untouched. The result’s that different weld options (comparable to soften pool or background) can seem extra pure and even because the vibrancy is elevated.
Examples with Totally different Tone Mapping
Determine 3. Unique Uncooked Picture. Be aware the darkish background and good element across the Arc. |
Determine 4. Shade Temperature Compensation turned on with Vibrance @ 30%, Tone Mapping S-Curve set with RGB coefficients of α=0.57, β=-0.24. The result’s a a lot brighter background with good definition of weld seam edges. |
Determine 5. Shade Temperature Compensation turned on with Vibrance @ 0%, Tone Mapping S-Curve set with RGB coefficients of α=0.57, β=-0.24. The result’s an excellent brighter background with some saturation occurring within the weld arc and torch space. |
Determine 6. – Shade Temperature Compensation turned on with Vibrance @ 30%, Tone Mapping S-Curve set with Purple coefficients set at α=1.0, β=0.0 and Inexperienced and Blue coefficients set at α=0.57, β=-0.24. This produces a reddish hue over your entire picture which appeals to some welders as they will see extra clearly options comparable to the vanguard of the soften pool as there’s a higher distinction between the soften pool and the guardian materials. |
Abstract
Shade photos can present extra data to a welder that isn’t usually observed in a monochrome picture, particularly for precision welding comparable to GTAW / TIG. In some very particular welding processes, the enhancement of the Tone Mapping processing utilizing particular person Look Up Tables could be an efficient software to customise the show of a picture and spotlight particular options of curiosity to a person welder.
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