Lasers have biological effects.

It's a very special thing, and high school students know that this thing has wave-particle duality.

Fluctuations, so that it has energy.

particles, so that they have an impact.

A specific wavelength of laser light can react with biological proteins, which is the principle of laser development fingerprinting.

Lu Chuan's intermediate fingerprint collection skill card analyzes the effect of different wavelengths of lasers on fingerprint collection.

A laser light source with an output wavelength of 445±5 nm and an output power greater than 13 watts can develop fingerprints on paper without loss.

Of course, fingerprints on leather and clothing can also be developed in this way.

However, the corresponding laser wavelengths are different.

With the instrument, Lu Chuan soon completed the fingerprint information collection on the envelope.

But that's not all.

What is needed on the economic investigation side is the fingerprint comparison results.

Lu Chuan's mood was more excited.

Because, the primary fingerprint identification and analysis skills rewarded by the system have finally come in handy.

Prior to this, whether it was in the arson case in the southern suburbs or in the case of the sinking of corpses in the reservoir, although Lu Chuan made great contributions to the collection of fingerprints.

But in terms of comparative analysis, I basically never participated.

This time is different, from the collection of fingerprints to the analysis and identification of fingerprints, Lu Chuan will complete it with one effort.

"Ding"

"Basic task: complete an excellent fingerprint identification analysis to determine the identity of the fingerprint owner."

The fingerprint collection on the envelope, although with the help of the variable frequency laser spectrum analyzer, has developed the fingerprint, but the integrity is not high.

And many of the thirty-nine fingerprints collected were superimposed.

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

In the first step, the fingerprint is pre-processed.

The prerequisite for the comparison of fingerprints is that the pre-processing of fingerprints should be in place.

It's like foreplay, and without adequate brewing, it dries up and is uncomfortable.

Fingerprint preprocessing involves many steps, and the requirements for different fingerprint preprocessing are different.

It's like different people, like different ways of foreplay, rough and gentle, and so on.

Broadly speaking, the preprocessing of fingerprints can be divided into two categories.

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

The shape is adjusted because there is a difference in shape between the fingerprints extracted from different carriers and the fingerprints collected normally.

For example, the fingerprint left on the flat surface of the index finger of the same person, because it is not disturbed by the outside world, the fingerprint is rounded and the shape is regular.

However, if the finger is held on the cup, the fingerprint will be affected by friction and slightly deformed, and the fingerprint will extend along the shape of the cup.

The resulting fingerprint is an elongated irregular shape.

Pre-processing is to try to eliminate the influence of strength and carrier shape on fingerprints, so as to increase the success rate for the later fingerprint comparison.

The purpose of marking feature points is to identify and compare fingerprints.

Any collected fingerprint can mark the endpoints, bifurcation points, divergence points and other feature points on the lines.

Fingerprint recognition is to use these points to judge the similarities and differences of fingerprints.

The primary fingerprint identification and analysis skills make Lu Chuan handy in the pre-processing of fingerprints.

Compared with the previous fingerprint preprocessing, Lu Chuan's feeling is smooth.

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

Lu Chuan did not use complex drawing software to adjust the fingerprint, but used the fingerprint adjustment software in the fingerprint automatic comparison system to adjust the shape.

In fact, many criminal police officers who are responsible for fingerprint comparison are reluctant to use the software that comes with the system.

Because the image adjustment software in the fingerprint automatic comparison system has a single function, it can only make limited adjustments to the fingerprint.

And there is a limit to the scope of adjustment.

But Lu Chuan is just the opposite, all the experience instilled in Lu Chuan in the primary fingerprint identification and analysis skills is completed through the image processing software that comes with the fingerprint comparison system.

In this way, there is an advantage that the comparison is more legitimate than the results.

This involves the question of the degree of fingerprint preprocessing.

The shape of the fingerprint is processed, and the size of the fingerprint and the gap of the texture are actually changed.

This is equivalent to changing the feature points of the fingerprint in disguise.

This is also the reason why the same fingerprint can be compared successfully after processing, and some people are unsuccessful after processing.

Ordinary image processing software, there is no limit, and the fingerprint can be adjusted without limits during preprocessing.

Therefore, many fingerprint comparisons need to be reviewed again by two or even three people to confirm whether the identification is successful.

And this review is actually to judge the degree of pretreatment deformation of the fingerprint.

Lu Chuan directly uses the drawing software that comes with the fingerprint comparison system, and the probability of successfully passing the review will be greater.

Because the system itself limits the degree of deformation of the fingerprint.

In front of the computer, Lu Chuan's eyes widened and his expression was excited.

The processing of fingerprints is different from what most people imagine, and it does not mean that after the fingerprint image is entered into the system, it can be compared.

This is a very meticulous job.

Boring, boring, even tormenting.

Of the pretreatment of 39 fingerprints, Lu Chuan successfully completed 27.

The remaining twelve fingerprints, because of the serious superposition and too many breakpoints, with Lu Chuan's current strength, there is no way to carry out valuable preprocessing.

However, twenty-seven fingerprints ......

That's enough.

The pre-processing of fingerprints was over, and it was already more than four o'clock in the afternoon.

The rest of the work is much simpler.

Twenty-seven fingerprints are entered into the system for automatic comparison.

Of course, it does not mean that the system comparison is successful, and the fingerprint identification and analysis is successful.

In other words, if the system comparison is not successful, the identification and analysis of fingerprints will fail.

In the current criminal investigation system, the automatic fingerprint comparison system will compare the fingerprints differently according to the characteristic points of the fingerprints.

Completely different fingerprints, which will be excluded at the first time, are the so-called fool comparison.

It's actually very fast, it's a comparison of data.

The so-called feature point does not mean that a point is marked and a circle is drawn.

Instead, it needs to go through a certain calculation to display the angle and coordinate data of each feature point in the form of coordinate axes.

Only then do the comparison take place within the system.

In this data, there must be some fingerprints with the same data for some feature points.

These fingerprints are automatically listed.

And according to the same amount of data, sort from high to low.

The data of all feature points is the same, which means that the fingerprint comparison is successful.

Putting the system running on its own, Lu Chuan turned on his mobile phone.

I looked at WeChat, and there were more than a dozen unread messages.

Mom: "I'll go out with your dad during the eleventh holiday, you can work overtime." ”

Since going to college, Lu Chuan suddenly had a feeling that he really seemed to be sending phone bills.

When I was in high school, I think I ate whatever I wanted.

When I went to college, I didn't have anything to eat.

Now that he goes to work, Lu Chuan doesn't dare to mention what he wants to eat.

Dad: "Your mother wants to go out to play during the eleventh holiday, do you want to accompany you?" ”

Lu Chuan grinned and decisively deleted Comrade Lu's information.

I'm going to accompany?

Hehe.

Most of the rest of the information is from a few classmates.

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