Flat-field correction is the most frequently used approach for vignetting correction. In this approach, the flat surface is uniformly illuminated with a uniform color. This approach is performed by following the steps given below:

The ISP plays a major role in processing the image taken from the sensor. Each ISP has a specific method to mitigate lens shading through a series of procedures. For instance, Imatest can be performed to test the image quality. ISO 17957 was implemented in the Imatest Uniformity and Uniformity Interactive (UI) modules. When the Imatest uniformity procedure is performed, you can view the lumination non-uniformity in the plot shown below.

The Absorbing Man suffers a setback when villain Norman Osborn uses an enchanted sword—provided by Loki—to remove his absorbing powers completely.[43]

An alternate version of Carl Creel from Earth-295 appears in Age of Apocalypse. This version works as a prison camp warden in Mexico.[84]

Vignettingin games

As discussed before, vignetting is an undesirable phenomenon, and it is impossible to fully prevent its occurrence. But it is necessary to use the methods for vignetting correction in embedded cameras to achieve the desired image quality. Let’s look at some of the approaches used to correct lens vignetting.

The CRA value of the lens must be less than the CRA value of the sensor’s microlens to eliminate the imaging illumination or color problems. Therefore, manufacturers must check the lens design to match their sensor layout.

Prabu is the Chief Technology Officer and Head of Camera Products at e-con Systems, and comes with a rich experience of more than 15 years in the embedded vision space. He brings to the table a deep knowledge in USB cameras, embedded vision cameras, vision algorithms and FPGAs. He has built 50+ camera solutions spanning various domains such as medical, industrial, agriculture, retail, biometrics, and more. He also comes with expertise in device driver development and BSP development. Currently, Prabu’s focus is to build smart camera solutions that power new age AI based applications.

Mechanical vignetting occurs when the light beam is mechanically blocked by the lens mount, filter rings or other objects, and causes shading towards the edges of the image. It is found mainly when the image format (or circle) of the lens is too small for the sensor’s size.

Natural vignetting is the decrease in Relative Luminance (RI) with respect to the field, and is governed by the ‘cosine fourth’ law of illumination fall-off. Here, the maximum brightness of the image circle produced by a lens with no vignetting is limited by the fourth power of the cosine of the CRA (Chief Ray Angle) in image space. This type of vignetting is also known as cos4θ roll-off. This is a natural phenomenon and can be addressed during post-production.

During the "Fear Itself" storyline, Creel and Titania encounter two of the divine hammers that contain the essences of the Worthy, generals to Odin's brother and adversary, Cul Borson. Coming into contact with the hammers, Titania and Creel were transformed into Skirn: Breaker of Men[46] and Greithoth: Breaker of Wills,[47] respectively. They later went on a rampage depicted in a number of Fear Itself tie-in issues, most prominently Avengers Academy #15–19 and Iron Man 2.0 #5–6, as well as that storyline's core miniseries.

During the "Opening Salvo" part of the "Secret Empire" storyline, Absorbing Man is recruited by Baron Helmut Zemo to join the Army of Evil.[55]

During the Dark Reign storyline, Creel joins a new version of the Lethal Legion led by the Grim Reaper.[41] After a defeat, Creel escapes prison and absorbs a shard of the Cosmic Cube.[42]

The Absorbing Man was featured in several scrapped scripts for Hulk, with one seeing him being reimagined as computer engineer Robert Creel.[116][117]

Vignettingin radiology

Creel's overall power increases in direct proportion to the material he duplicates. There seems to be almost no limit to what Creel absorbs, as he have mimicked the properties of bronze;[68] Odin's Cosmic Bolt and later cyclonic storm;[69] diamond;[70] glass;[71] light;[24] rock, silk, soil;[72] spikes;[73] steel;[63] Thor's uru hammer Mjolnir;[74] water;[65] and even the whole realm of Asgard itself,[69] although draining the Sentry's energies proved too much for Creel, causing him to become overloaded with it and nearly killing him.[38] Creel is also now capable of combining previously absorbed abilities.[75]

CRA is one of the important parameters for the selection of lenses and sensors. It affects the image quality by creating shadows on the image edges. The actual CRA of the lens is dependent on the lens design, not the sensor – and is determined by the rays passing through the lens. The efficiency of the light incident on the CMOS or charge-coupled device (CCD) sensor is not only related to the CRA but also related to the microlens of the sensor.

The Absorbing Man (Carl "Crusher" Creel) is a character appearing in American comic books published by Marvel Comics. Created by writer Stan Lee and writer-artist Jack Kirby, the character first appeared in Journey into Mystery #114 (cover dated March 1965), in the Silver Age of Comic Books.[4][5] Carl Creel has the power to absorb and become any material he touched.[6][7][8] Originally a supervillain, in later years, he has reformed into more of an antihero.[9]

When Absorbing Man and Titania were robbing an armored car, the female Thor appeared to thwart their plans. Upon meeting the female Thor, Creel mocked her for being a woman and for having taken Thor's name for herself, which she answered by breaking his jaw. Titania then appeared to confront her but, in respect for what she was doing, she knocked out her husband with his own weapon and surrendered.[51]

After Absorbing Man was imprisoned for another crime, his lawyer convinced him to join the U.S. Hulk Operations as an alternative to getting incarcerated for life. He gets injected with a Bannerman Gene-Enhancement Package that turned him into a gamma mutate able to absorb gamma radiation, at the cost of turning his skin a bright red color. When Absorbing Man - under the alias of Red Dog - fought Hulk at Los Diablos Missile Base, an entity, the One Below All entered his body after he absorbed most of the Hulk's gamma energy. The One Below All taunted Red Dog's astral body before ripping his physical one in half.[61] Absorbing Man, still controlled by The One Below All, continues fighting Hulk. Absorbing Man ran off when Jackie McGee, Walter Langkowski, and Puck showed up. When the One Below All successfully opened the door to the Below Place, the lowest point of Hell, the entirety of New Mexico gets transported there as Absorbing Man weeps.[62] With the help of Puck, Creel was able to transfer the gamma energy he had absorbed back into Hulk, who used his thunder clap to disperse the One Below All's cloud form and transport New Mexico back to Earth. Creel has since been free of the One Below All's influence, having transferred the gamma radiation back to the Hulk, joining Gamma Flight in the process.[3]

However, Creel goes on to battle many other heroes, such as the Avengers,[22] Daredevil,[23] the Dazzler,[24] the Hulk,[25] and Spider-Man.[26] He is one of the villains who participates in the Secret Wars, and also develops a romantic relationship with the super-strong villainess Titania.[27] The pair also join the reformed fourth version of the Masters of Evil.[28] Creel has several more battles with Thor[29] (and the Eric Masterson Thor)[30] and a skirmish with the cosmic hero Quasar.[31] Although he assisted Crossbones in a plan to attack Captain America, when Absorbing Man learned that Crossbones intended to detonate a bomb in New York, he absorbed the properties of Captain America's shield to contain the blast, declaring that he was not a murderer.[32]

Vignettingin film

Carl Creel has the ability to mimic the matter or strength of anything nearby or anyone he is near.[63][64] Most commonly, the Absorbing Man uses his powers to duplicate the qualities of anything that he touches—solids, liquids, gases, or even energy sources. This transformation also extends to the items that Creel was wearing and carrying when Loki's magic potion took effect (for example, if Creel touches the metal titanium, his body, clothes, and wrecking ball takes on its appearance and properties). He can absorb sufficient mass from a large object (e.g., a building) to attain the same height. While in different alternate forms, he still maintains his intellect, capacity for speech, and full physical movement (although his first attempt at absorbing water temporarily cost Creel's sanity when he tried to keep himself from drifting apart in the ocean).[65] His body was able to reform itself after being broken or damaged,[66] especially a severed arm which Wolverine cuts off during the Secret Wars.[67]

In the uniform luminance result, the side and corner regions are shown as red rectangles. A yellow circle indicates the approximate location of the maximum luminance. L R T B values are the luminance values at the left, right, top and bottom sides of the averaged image file respectively. The UL (Upper Left), LL (Lower Left), UR (Upper Right), and LR (Lower Right) values are the luminance values of the four corners. Based on the above luminance uniformity result, the specific registers in ISP can be tuned or calibrated.

Vignettingpronunciation

There are two types of light ray roll-off vignetting – optical vignetting and natural vignetting. Optical vignetting is caused due to the reduction in effective lens opening for off-axis incident light. This results in a gradual decrease of the brightness towards the image periphery – depending on the physical dimensions of a multiple-element lens.

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VignettingWitcher 3

Complementary Metal Oxide Semiconductor (CMOS) is the most common type of image sensor used in today’s embedded vision applications. CMOS cameras receive light to form a pixel array. These cameras need the right optics (or lens) to be able to capture image data ready for the various types of processing mentioned before. However, picking the best-fit lens and integrating it with the camera module comes with its own set of challenges. These include determining the right FOV (field of view) for the application, choosing the right focus type (fixed focus or autofocus), fixing the working distance, etc. To make it worse, phenomena like lens vignetting and white balance issue also corrupts the image output.

Vignettingphotography

Creel and Titania later come into conflict with the heroine She-Hulk and her Skrull partner Jazinda after they attempt to arrest Creel's cousin Rockwell "Hi-Lite" Davis.[40]

As you can see in the above illustration, all the rays are focused onto the active area of the pixel if the light is focused at normal incidence. Not all rays make it to the active pixel area at an oblique incidence.

Lens vignetting refers to the gradual reduction of an image’s brightness or saturation from the image center to the four corners/edges. Also known as lens shading, light fall-off or luminance shading, it depends on the lens aperture and several lens design parameters. This fall-off is measured in f-stops.

Carl "Crusher" Creel was a boxer and jailed criminal who becomes the Absorbing Man when he drinks a liquid which the Asgardian god Loki laced with a mystical potion.[13][14] Discovering that he could absorb the properties of anything he touched, Creel escapes prison by absorbing metal from the guards' bullets and goes on to battle Thor.[15] When he escapes, he takes with him the ball and chain to which he was shackled, and uses the ball and chain as a weapon. Although he is only mortal, Creel's fantastic abilities make him a worthy opponent for Thor, who is later forced to end the battle due to Loki's kidnapping of Jane Foster.[16] Creel then breaks into a house and attacks the occupants. Thor comes to the rescue and tricks Creel into changing his atomic structure into pure helium. Thor accomplishes this by using his hammer's powers to transform the ground's molecular makeup. As Creel is acquiring additional mass from direct contact with the Earth when this happens, he ends up drifting harmlessly into the atmosphere.[17][18]

Since his original introduction in comics, the character has been featured in various other Marvel-licensed products, including video games, animated television series, and merchandise such as trading cards. He appears in the Marvel Cinematic Universe TV series Agents of S.H.I.E.L.D., portrayed by Brian Patrick Wade.

Drew Atchison of Screen Rant included Absorbing Man their "Hulk's Main Comic Book Villains, Ranked Lamest To Coolest" list, writing, "Teaming up with the Inhuman king, Black Bolt, to siding with Gamma Flight to take on the Immortal Hulk, Carl's been through a lot and deserves to return to the MCU."[76] Comic Book Resources ranked Absorbing Man 3rd in their "10 Strongest Marvel Henchmen" list,[77] 4th in their "10 Villains Fans Hope To See In Marvel’s She-Hulk Series" list,[78] 4th in their "10 Best B-List Avengers Villains" list,[79] 5th in their "Top 10 She-Hulk Villains" list,[80] 5th in their "10 Strongest Marvel Human Villains" list,[81] 6th in their "Age Of Apocalypse: The 30 Strongest Characters In Marvel's Coolest Alternate World" list,[82] 7th in their "Hulk’s 10 Most Powerful Villains" list,[14] 8th in their "Marvel: 10 Villains Who Keep Getting Stronger" list,[83] 9th in their "Thor: 10 Most Dangerous Villains He's Ever Fought" list,[64] and 12th in their "Hulk's 20 Most Powerful Enemies" list.[20]

An alternate version of Carl Creel from Earth-58163 appears in House of M. This version is a member of the Hood's Masters of Evil.[86]

We hope that this blog helped clear all your doubts about lens vignetting. If you have any further queries on how you can overcome this issue in your embedded vision applications, please leave a comment.

Natural vignetting or cos4θ roll-off can be avoided if the lens is stepped down by two f-stops that increase the numerical f-stop number.

During the "Avengers: Standoff!" storyline, Absorbing Man was an inmate of Pleasant Hill, a gated community established by S.H.I.E.L.D. Using Kobik, S.H.I.E.L.D. transformed Absorbing Man into a man named Harold.[53] During his time as Harold, Absorbing Man ran an ice cream parlor and was in love with Sheriff Eva. When Helmut Zemo and Fixer restored the memories of the inmates, Absorbing Man joined in on their uprising with Whirlwind. Illuminati members Hood and Titania arrived at Pleasant Hill to retrieve Absorbing Man. Although he was shaken from having a S.H.I.E.L.D.-induced normal life, Absorbing Man sides with the Illuminati as they work to assemble the other inmates to get revenge on S.H.I.E.L.D.[54]

At some point, Absorbing Man was imprisoned in a deep space torture prison. He was defeated by Black Bolt in combat.[56] Absorbing Man later made an acquaintance with Black Bolt and fellow inmates Blinky, Metal Master, and Raava.[57] Upon taking in Black Bolt's sonic scream, Absorbing Man seemingly sacrifices himself to help destroy the torture prison's Jailer, enabling Black Bolt and the other inmates to escape.[58] At the time when Jailer has possessed Blinky's mind to kill Black Bolt, Lockjaw took Titania to Parkwood Cemetery where Absorbing Man suddenly emerged from his grave.[59] Absorbing Man and Titania helped Black Bolt fight a Jailer-possessed Blinky until they managed to drive Jailer out of him.[60]

Creel regains his powers and storms Avengers Tower to recover his ball and chain. He is defeated by Avengers' coordinators Maria Hill, Sharon Carter, and Victoria Hand after absorbing the latter's cold.[45]

Creel is later incarcerated in New York's experimental "Ant-Hill" prison called the Big House, where all prisoners are reduced in size via Hank Pym's "Pym Particles". An escape attempt is thwarted by She-Hulk.[33]

During the "AXIS" storyline, Absorbing Man appears as a member of Magneto's unnamed supervillain group during the fight against Red Skull's Red Onslaught form.[48] He is briefly converted to heroism when everyone on the island experiences a moral inversion as Doctor Doom and Scarlet Witch attempt to bring out the Charles Xavier in Red Skull, joining the new Astonishing Avengers assembled by Steve Rogers and Spider-Man to oppose the inverted heroes.[49] Absorbing Man later reverts to villainy when the inversion is undone.[50]

The Absorbing Man debuted in Journey into Mystery #114 (March 1965), created by Stan Lee and Jack Kirby.[10] He appeared in the 2017 Black Bolt series, by Saladin Ahmed.[11][12]

Vignetting can also be caused in cases like lower f/#s (ratio of the focal length to the aperture size), short focal length lenses, or lenses where higher resolutions need to be achieved at a lower cost. Mechanical vignetting is the only type that can be eliminated by using a camera technique (using a longer focal length).

Vignettinglens

During the "Secret Wars" storyline of 2015, Absorbing Man is among the villains attending Kingpin's viewing party of the incursion between Earth-616 and Earth-1610.[52]

Several software tools such as microscopy image stitching tools, CamTool, etc., are available for lens shading correction.

A short time later, Loki retrieves Creel from space using Asgardian technology after he has knocked out an Asgardian warlock and sends Creel back to battle Thor. After Creel is nearly beaten due to Thor's fighting skill, Loki transports him to Asgard and reveals the true source of his "absorbing" powers. After being humbled by Loki, Creel agrees to act as his agent, and he is directed to take over the city. The Absorbing Man defeats the Asgardian legions without too much trouble and eventually confronts Odin himself. Creel absorbs Odin's attacks and then the properties of Asgard itself, hoping to rule the universe, and he towers over Odin as Loki arrives to gloat. Thor is ordered by Odin not to keep attacking. Loki and Creel are then beaten by trickery; once given Odin's Rod of Rulership the two quarrel over it, with the Absorbing Man trying to absorb the rod, and the two find that they cannot let go. Odin then advises them that his power lies not in a mere object, but deep within himself. The pair are then banished into outer space.[19][20]

Some of the causes of lens vignetting can be the optics itself. The phenomenon can be increased/intensified due to blockage of the light beam by using external tools like filters, filter holders and lens hoods. At times, it is also added in post-processing to draw the viewer’s eye away from the distractions in the corner and towards the center of the image.

Vignettingmeaning

An alternate version of Carl Creel from Earth-807128 appears in Old Man Logan.[90][91] Additionally, a gang inspired by him called the Creel Gang also appears.[92][93][94]

Manufacturers can design lenses to be image space telecentric to correct roll-off, as this telecentricity produces extremely uniform image plane illumination. Since all chief rays have an angle of θ with respect to the image plane, the normal cos4θ fall-off in the image plane illumination from the optical axis to the corner of the field is removed.

The aperture controls the image’s brightness by altering the overall amount of light that reaches the camera sensor through the lens. The below test image shows luminance shading from center to the four corners.

Image processing platforms are rapidly advancing to provide reliable and cost-effective embedded vision solutions across different markets. Some of the common image processing techniques can improve the image quality by correcting illumination, rescaling the image (digital zoom), detecting edges, evaluating and ranking segmentation algorithms, etc. They do so by leveraging image enhancement, restoration, encoding, and compression. Many image sensors integrate these image processing modules on a chip circuit.

The Absorbing Man eventually returns on a comet and battles the Hulk. Bruce Banner had been sent to divert the comet, as it was feared it was radioactive, but the Absorbing Man leaped aboard and began absorbing the Hulk's strength. He tries to bury the Hulk under a mountain, but when the Hulk turns back to human form, the Absorbing Man is unable to support the great weight and was buried.[21]

The Absorbing Man later battles and is apparently killed by the hero Sentry during the events of Civil War.[38] However, he later appears at the funeral of the villain Stilt-Man.[39]

An alternate version of Absorbing Man from Earth-95019 appears in Marvel Apes. This version is a mandrill called Absorbing Mandrill and a member of the Master Brotherhood of Evil Apes.[88]

The Absorbing Man escapes prison and allies with the Owl as an enforcer,[34] but finds himself opposed by Spider-Man and new hero Ethan Edwards (later revealed to be a disguised Skrull). He is briefly trapped and converted into a new form of cocaine by one of the Owl's operatives when they become frustrated with his unprofessional approach,[35] with the new drug briefly giving those who snort him a degree of his powers, but he eventually manages to reassemble himself in a sewer and goes after the Owl for revenge.[36] Spider-Man manages to defeat Creel by tricking him into running a gauntlet where he absorbs multiple objects thrown at him, culminating in Creel absorbing two different chemicals that cause him to explode.[37]