The laser has biological effects.

Light is a very special thing, as even high school students know, it has both wave and particle duality.

Waves give it energy.

Particles give it impact.

Laser with specific wavelengths can react with biological proteins, which is the principle behind using lasers to develop fingerprints.

In Lu Chuan's Intermediate Fingerprint Collection Skills card, there is an analysis of the effects of different wavelength lasers on fingerprint collection.

A laser source with a wavelength of 445±5 nanometers and output power greater than 13 watts can non-destructively develop fingerprints on paper.

Of course, fingerprints on leather and clothes can also be developed using this method.

However, the corresponding laser wavelengths are different.

With the equipment, Lu Chuan quickly completed the fingerprint information collection on the envelope.

But this is not the end.

The economic investigation department needs the fingerprint comparison results.

Lu Chuan felt quite excited.

Because the Basic Fingerprint Identification Analysis skill rewarded by the system is finally coming into play.

Before this, whether it was in the South Suburb arson case or the reservoir corpse case, although Lu Chuan made significant contributions in fingerprint collection,

he had basically never participated in comparison analysis.

This time is different; Lu Chuan will complete the process from fingerprint collection to identification analysis on his own.

"Ding"

"Basic Task: Complete an excellent fingerprint identification analysis to determine the identity of the fingerprint owner."

Although the fingerprint collection on the envelope, with the help of a frequency-conversion laser spectrum analyzer, revealed the fingerprints, the completeness is not high.

Moreover, many of the thirty-nine collected fingerprints overlap with each other.

What Lu Chuan needs to do now is to compare and analyze all the fingerprints, and find their owners as much as possible.

The first step is to pre-process the fingerprints.

The prerequisite for fingerprint comparison is that fingerprint pre-processing must be in place.

Fingerprint pre-processing involves many steps, and the requirements for different fingerprint pre-processing are different.

In general, fingerprint pre-processing can be divided into two categories.

One is to adjust the fingerprint shape, and the other is to mark fingerprint feature points.

Adjusting the shape is because fingerprints extracted from different carriers have shape differences compared to normally collected fingerprints.

For example, the fingerprint left by the same index finger on a flat surface is smooth and regularly shaped because it has not been subjected to external interference.

But if the finger is holding a glass, the fingerprint will be slightly deformed due to the friction, and the cylindrical shape of the glass will cause the fingerprint to extend along the shape of the glass.

The fingerprint collected like this is an irregular long oval shape.

Pre-processing aims to eliminate the influence of force and carrier shape on the fingerprint as much as possible, thereby increasing the success rate of subsequent fingerprint comparison.

Marking feature points is for fingerprint recognition and comparison.

Any collected fingerprint can have endpoints, bifurcation points, and divergence points marked on its ridges.

Fingerprint recognition relies on these points to determine the similarities and differences of fingerprints.

The Basic Fingerprint Identification Analysis skill allows Lu Chuan to handle fingerprint pre-processing with ease.

Compared with previous fingerprint pre-processing efforts, Lu Chuan feels smooth.

In front of the computer screen, a fingerprint is being enlarged right in front of Lu Chuan's eyes.

Instead of using complex drawing software for fingerprint adjustment, Lu Chuan used the fingerprint adjustment software in the fingerprint auto-comparison system for shape adjustment.

In fact, many police officers responsible for fingerprint comparison are reluctant to use the system's built-in software.

Because the image adjustment software in the fingerprint auto-comparison system is single-function, only allowing limited adjustment of fingerprints.

Moreover, the range of adjustments is restricted.

But Lu Chuan is quite the opposite. All the experience imparted to him in the Basic Fingerprint Identification Analysis skill is completed through the system's built-in image processing software.

This has one advantage: the legality of the comparison results is higher.

This involves the issue of the level of fingerprint pre-processing.

Processing the fingerprint shape actually changes the size and ridge gap of the fingerprint.

This is equivalent to indirectly changing the fingerprint's feature points.

This is why the same fingerprint can be successfully compared by some while others cannot after processing.

Ordinary image processing software has no restrictions, allowing unlimited adjustments to fingerprints during pre-processing.

Therefore, many fingerprint comparisons require verification by two or even three people to confirm whether the identification is successful.

This verification is actually an assessment of the extent of fingerprint pre-processing deformation.

By using the system's built-in drawing software, Lu Chuan has a higher probability of successfully passing the verification.

Because the system itself limits the level of deformation processing on the fingerprint.

In front of the computer, Lu Chuan's eyes widened with excitement.

Fingerprint processing, unlike what most people imagine, isn't about inputting the fingerprint image into the system and getting results.

It's a detailed-oriented work with very high accuracy requirements.

Monotonous, uninteresting, even torturous.

Lu Chuan successfully completed the pre-processing of twenty-seven out of thirty-nine fingerprints.

The remaining twelve fingerprints are too overlapped and broken, and Lu Chuan currently doesn't have the capability to perform valuable pre-processing on them.

However, twenty-seven fingerprints...

Are enough.

The fingerprint pre-processing concluded just after 4 PM.

The remaining work was much simpler.

Just input the twenty-seven fingerprints into the system for automatic comparison.

Of course, the system's successful comparison doesn't mean that the fingerprint identification analysis is successful.

Or if the system doesn't successfully compare, it doesn't mean the fingerprint identification analysis failed.

Currently, in the criminal investigation system, the fingerprint auto-comparison system performs similarity comparisons based on the number of fingerprint feature points.

Completely different fingerprints will be excluded immediately, which is what's called a foolproof comparison.

This is actually fast, as it's just a data comparison.

The so-called feature points are not just marking a point and drawing a circle.

They require a certain amount of calculation, displayed in the form of coordinates, showing each feature point's angle, coordinate data.

Then only can they be compared within the system.

Among these data, certain fingerprints will definitely have some feature point data that are the same.

The system will automatically list these fingerprints.

And it will rank them from highest to lowest based on the amount of identical data.

All feature point data being completely identical signifies a successful fingerprint comparison.

Letting the system autonomously carry out the comparison, Lu Chuan opened his phone.

Looking at WeChat, there are more than ten unread messages.

Mom: "During the National Day holiday, your dad and I are going out to play, you should work overtime."

Since starting college, Lu Chuan suddenly felt as if he was really just a bonus for topping up his phone credit.

Back in high school, he could eat whatever he wanted.

After entering college, what he wanted to eat wasn't there.

Now that he's working, Lu Chuan doesn't even dare to mention what he wants to eat.

Dad: "Your mom wants to go out during the National Day holiday, do you want to accompany her?"

Lu Chuan grinned and decisively deleted the message from Comrade Lu.

Accompany them?

Haha.

The remaining messages were mostly from a few classmates.

What caught Lu Chuan's eyes was a message from three minutes ago.

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