Runco REFLECTION CL-510 Manual de usuario descargar pdf (Pagina 21)

TECH CORNER

Fall 2003 ExtroNews 14.3 21

Phase

The phase adjustment of a scaler is

used to manipulate where on a pixel a

scaler takes a sample. Where the clock setting

adjusts how many pixels will be sampled,

the phase adjusts what part of the pixel the

sample will be taken from. Consider Figure 6.

By changing the phase adjustment of the

ISS 408, adjusting the point at which pixels

are sampled, the image can be sampled

at the perfect place upon the pixel, which

gives the clearest, sharpest image [see

Figure 6-1]. Sampling at the wrong point

on the pixel will result in an image that

“shimmers” with noise. Sampling on the

leading or falling edges of the pixels, [Figure

6-2], results in an image gray with noise.

Auto-Image

™

So now to the Auto-Image feature, where

again one might ask, “Why would I adjust

manually what the scaler can do automatical-

ly?” The answer to that question would be

that you wouldn’t, or you would just check to

see if the scaler did it right. But that leads to

another question: will the scaler do it right?

Most of the time it will, though some-

times minor adjustments may be necessary

to perfect an image. To clarify, let’s discuss

how Auto-Image works.

When a scaler such as the ISS 408 “sees”

an image, it must identify the signal to de-

cide what to do with it. This can be done

after the scaler has digitized the video and

sync information by measuring parameters

of the signal. Then, the scaler can:

• Pull up a memory saved for that

incoming signal’s parameters to dictate

size, position, clock, and phase.

• Load default settings for signals

not previously saved.

• Auto-Image, or generate a new set

of parameters, to dictate the size,

position, clock, and phase.

When the scaler performs the Auto-Image

function, it looks at video parameters math-

ematically, such as active video timing, sync

timing, and blanking interval, and uses these

parameters in an algorithm that calculates

the settings. But w

hen is it appropriate to use

the Auto-Image feature, as apposed to recall-

ing settings or applying factory defaults?

To answer this question, let’s look at why

Auto-Image is a useful feature:

• Auto-Image dials in 90% of all images

close to perfect the ﬁrst time.

• Auto-Image works with video signals new

to the scaler and with signals that have

been encountered by the scaler before.

Optimizing Your Image with Auto-Image (continued)

Figure 6-1: Sample phase set correctly Figure 6-2: Sample phase set incorrectly

OUT

PROCESS

H-Line

Output

Pixel on / Pixel off

PROCESS

H-Line

Input

Pixel on / Pixel off

Samples aligned on

stable portion of pixels

Samples aligned on

rising and falling edges

RESULT

continued on page 22

Figure 6: Examples of correctly and incorrectly phased signals.

at best. Setting a scaler’s clock to sample pix-

els 1:1 in challenging applications is crucial to

generating good image quality. Figure 5-2

shows the artifacts that will occur with under

sampling an image. Over sampling [Figure 5-

3], can cause artifacts as well, especially when

sampling at a rate close to 1:1. Sampling at a

rate of 1:1 [see Figure 5-1] will generate the

best image.

It is important to note that adjusting the

vertical size also adjusts whether or not

certain artifacts will be present. Since a vertical

size adjustment manipulates the number of

lines of active video present on the output,

artifacts such as horizontal line loss, or lack of

consistent horizontal line brightness, can be

present if the vertical size setting is not set to

scan one line out for every line sampled in.

1 2 ... 16 17 18 19 20 21 22 23 24

Comentarios a estos manuales

Sin comentarios

Runco REFLECTION CL-510 Manual de usuario Pagina 21

Comentarios a estos manuales

Relacionado con productos y manuales para Proyectores Runco REFLECTION CL-510