(Unit 0) Intro 1: Rendering
Summary
TLDRIn this introductory lecture for Comp 3490: Computer Graphics One, the instructor delves into the foundational concept of rendering, which is the process of translating data into visual displays. The lecture emphasizes the importance of pixels, the smallest individually accessible display elements, predominantly squares but with alternatives like anamorphic (rectangular) and non-rectangular pixels such as hex pixels. The instructor also introduces raster graphics, explaining how they are composed of a grid of pixels, and touches on various file formats like JPEG, PNG, and BMP that are used to store these pixel grids. The lecture aims to provide students with a solid understanding of the basics of computer graphics, setting the stage for more advanced topics in the course.
Takeaways
- 🎓 The lecture is part of the COMP 3490 course on computer graphics, focusing on the basics and building blocks of the subject.
- 🖼️ Rendering is defined as the process of converting abstract data into a visual display on a screen, which is a fundamental problem in computer graphics.
- 🔍 The lecturer introduces pixels as the smallest individually accessible display elements, typically squares, but with alternatives like anamorphic and non-rectangular pixels.
- 📐 Anamorphic pixels are non-square, rectangular pixels used in certain displays like TVs where one dimension is more important than the other.
- 🔲 Non-rectangular pixels, such as hex pixels, were used in early computer graphics for benefits like reduced aliasing and free transformations.
- 🎨 Raster graphics are graphics made up of a grid of pixels, with each pixel having a specific color, used in common formats like JPEG, PNG, and BMP.
- 🌐 The course will mainly deal with rendering, which is central to computer graphics, though other forms of graphics like vector graphics are not covered in this course.
- 🖼️ When zooming in on a raster graphic, like a leaf, it appears as a grid of square blocks, which is the essence of raster graphics.
- 📚 The script suggests that understanding the basics of raster graphics is important for grasping how images are displayed and manipulated in computer graphics.
- 📈 The course appears to be interactive, with the lecturer encouraging students to experiment with raster graphics to deepen their understanding.
- 🔄 The script mentions that while some modern programs may hide the pixel grid for a smoother appearance, it's crucial for learning to see the underlying structure.
Q & A
What is the main focus of the first lecture in COMP 3490 Computer Graphics?
-The main focus of the first lecture is to introduce the fundamental problem of rendering in computer graphics, which is the process of converting abstract data into a visual display on a screen.
What is rendering in the context of computer graphics?
-Rendering in computer graphics is the process of converting abstract data structures into a visual representation on a display screen.
What are pixels in the context of computer graphics?
-Pixels are the smallest individually accessible display elements that can be read and written to, typically represented as squares on a screen.
What is an alternative to square pixels that is commonly used in certain displays?
-An alternative to square pixels is anamorphic pixels, which are non-square and rectangular, often used in displays where one dimension is more important than the other, such as TVs.
Why might anamorphic pixels be used in video compression systems?
-Anamorphic pixels are used in video compression systems to compress one direction more than the other, resulting in rectangular pixels, which can be beneficial for certain displays like TVs where one dimension is more important.
What is the issue that can occur if anamorphic pixels are not set up correctly during video conversion?
-If anamorphic pixels are not set up correctly during video conversion, the image may appear squished or distorted due to incorrect pixel settings.
What are non-rectangular pixels, and why were they used in the past?
-Non-rectangular pixels, such as hex pixels, are a type of pixel that is neither square nor rectangular. They were used in the past for certain specialized hardware and applications due to benefits like reduced aliasing and the ability to provide free transformations.
What is the advantage of hex pixels in terms of image transformations?
-Hex pixels offer the advantage of providing five free transformations compared to the three that square pixels offer, which can be beneficial in systems where rotations are needed without losing data.
What is raster graphics, and how is it related to pixels?
-Raster graphics is a type of graphic made up of a grid of pixels. Each pixel in the grid has a color, and shapes are created by coloring the pixels, similar to coloring on graph paper.
What are some common file formats that use raster graphics?
-Common file formats that use raster graphics include JPEG, PNG, BMP, and PCX. These formats provide different features such as compression and lossless detail.
Why might some modern graphics programs not show the individual square blocks when zooming in on an image?
-Some modern graphics programs may not show individual square blocks to provide a cleaner and more visually appealing representation, although this can make it harder to understand the underlying raster graphics structure.
Outlines
🎨 Introduction to Computer Graphics and Rendering
The first paragraph introduces the course COMP 3490: Computer Graphics. The lecturer mentions that the previous class was an introduction to the course and computer graphics, and there's nothing significant to remember from it. The focus of the current lecture is on the fundamentals of computer graphics, specifically rendering. Rendering is defined as the process of converting abstract data into a visual display on a screen. The lecturer emphasizes that rendering is a central theme throughout the course. The concept of pixels as the smallest individually accessible display elements is introduced, and the importance of their accessibility for reading and writing is highlighted. Pixels are typically square, but alternatives are mentioned, setting the stage for a deeper dive into rendering and pixel structures.
📐 Understanding Pixels and Raster Graphics
The second paragraph delves deeper into the concept of pixels, explaining that while they are predominantly square, there are alternatives such as anamorphic (rectangular) and non-rectangular pixels like hex pixels. Anamorphic pixels are used in certain displays where one dimension is more important than the other, such as in TV screens, and can be encountered in video encoding and old CRT displays. Hex pixels, which are less common, offer benefits like reduced aliasing and additional free transformations, which were particularly useful in early hardware and specialized applications. The paragraph also introduces raster graphics as images composed of a grid of pixels, each with a color value, allowing for the creation of shapes and images by manipulating these pixels. The concept is fundamental to various image formats like JPEG, PNG, BMP, and PCX, which are all variations of raster graphics, each with its own compression and detail preservation techniques.
🖼️ Exploring Raster Graphics and Image Formats
The third paragraph continues the discussion on raster graphics, providing examples of different image file formats such as JPEG, PNG, TIFF, and BMP, which are all based on the raster graphics format. It explains that JPEG uses a type of compression based on Fourier techniques, while BMP does not use compression, and PNG offers lossless compression, preserving all details. TIFF is mentioned as being more suited for cameras and printing. The lecturer suggests an exercise for students to zoom into an image using their favorite painting tool to observe the grid of pixels that make up the image, emphasizing the importance of understanding the underlying structure of raster graphics. The paragraph ends with a note on the lecturer's intention to continue the topic in the next part of the video.
Mindmap
Keywords
💡Rendering
💡Pixels
💡Raster Graphics
💡Anamnorphic Pixels
💡Hex Pixels
💡Data Structures
💡Display Screen
💡Image Formats
💡Compression
💡Aliasing
Highlights
Introduction to the course COMP 3490: Computer Graphics One.
Explanation of rendering as the fundamental problem in computer graphics, which is converting data to display.
The concept of pixels as the smallest individually accessible display elements.
Pixels are predominantly square in shape for simplicity in rendering.
Alternative pixel shapes include anamorphic (non-square, rectangular) pixels used in certain displays and video compression.
Older formats of non-rectangular pixels like hex pixels used in specialized hardware and early computer graphics.
Benefits of hex pixels include reduced aliasing and additional free transformations.
Raster graphics defined as images composed of a grid of pixels.
Different file formats like JPEG, PNG, BMP, and PCX are variations of raster graphics.
JPEG uses Fourier-type compression, while PNG is lossless and does not lose any detail.
TIFF is designed for professional cameras and printing, offering features for high-quality imaging.
Raster graphics are popular and used in common image formats like JPEG and PNG.
Demonstration of raster graphics by drawing a simple grid and coloring pixels to form shapes.
The importance of understanding the underlying grid of pixels in raster graphics for proper learning and application.
The video lecture will continue with more topics related to raster graphics and computer graphics in general.
Transcripts
hello welcome to the first
video recorded lecture of comp 3490
computer graphics one
all right so last class
we just did a quick introduction
so you didn't miss anything um there's
nothing to really remember
just an intro to the course
and an intro
to computer graphics
that's all we did so today we're really
going to get started with
the nitty gritty starting to learn the
first pieces starting to learn
the building blocks of computer graphics
that's today
all right so i'm going to start by
talking about rendering
uh rendering is a fundamental problem in
computer graphics
and you might have heard about people
talking about rendering before
it's not a big deal to understand it
it's simply the problem of going from
going from data to display it's from
data to display that's all that
rendering is
so you can imagine now that in your
program in memory
you have maybe a linked list of some
kind of data structure
maybe a tree whatever you have a game
map that you've stored
you've loaded in some images
right you have some points that you want
to render
so you have all this data but it's it's
pretty abstract
the rendering is simply the problem of
going from
that abstract data to something on your
display screen
that's it
and most of this course will be dealing
with rendering
in one form or or another
right so you have all this abstract data
and maybe when you run it on your screen
you get a nice
happy face right okay
i'm going to highlight these by the way
i'm really bad with being consistent
with my highlighting
so the colors don't really mean much
except for pay attention to them
so the first thing i want to talk about
when it comes to rendering are pixels
again you've probably heard about pixels
before but i want to talk about them a
little bit more
than you might have thought about them
before what are pixels
pixels are simply the smallest come on
there we go pixel's a smallest
individually
accessible
display elements
so this accessible is the key here you
can read and write them
right you can put them you can read them
and see what they look like
uh sorry give them a color and also see
what's already on the screen
predominantly these are
predominantly these are squares but i
will talk a little bit
about some alternatives so pixels are
generally squares predominantly
squares and there's no
real reason for this be except for the
fact that it's
for simplicity um maybe i'll jump over
to um
my slide real quick just to show what i
mean by this
so here's my that work i hope that works
um i don't think that works the way i
think it works
let me just change no presenter view
this i think that's right aha this is
what i wanted
all right so here's an example i have a
screen this is an old computer screen
commodore 64 something from the 80s
and you see this blocky font was very
common but if you zoom in
you see we have these square pixels in
this case they're on or off
off as black on is blue or it could be
white or green
and you take a letter like the a or the
r you look inside
and it's made up of these little square
blocks called pixels kind of like a
minecraft world
um so that's all that that pixels really
are
okay i can go back to my ipad so they're
predominantly squares
um there are alternatives i'll talk
about that but you won't really deal
with these
in this course but it's important to
know that alternatives exist
the most common alternative these days
we call
anamorphic
so we have anamorphic pixels now this
sounds really exciting anamorphic
they're going to come a lot no
nope all that anamorphic pixels mean
are non-square uh rectangular like this
and
we do this we do this because
on certain displays one dimension is
more important than the other
typically on a tv you have a lot of
pixels this way
and a few this way so you'll have
video compression systems that'll
actually have anamorphic pixels and
they'll compress one direction more than
the other your pixels become
rectangular instead of square you'll
come across this if you do video
encoding stuff
if you're with old crt displays you hear
about anamorphic pixels
all that it means is they're not square
they're rectangular
and you have to do some math to convert
them um you might have seen this if
you've done a video conversion and it
went wrong and the image looked squished
or squished you just had the wrong pixel
setting
but we won't really deal with anamorphic
pixels in this course
these are typically for dvd blu-ray
that world or tv
um yeah you can read up on this if
you're interested
but um don't spend too much time on it
there's also another
format and this is really dated now we
don't see much of this anymore
but you will see this in special use
cases and those are non-rectangular
pixels non-rectangular
so it's not square and they're not
rectangular what's left now let's let's
see if i can draw this
um one format that was pioneered in the
early days
were hex pixels and if any of you have
ever played
tile based for board games i'm going to
screw this up
there we go um you might be thinking oh
that's kind of neat
why on earth would people do hex pixels
there are actually a lot of benefits to
these kinds of hex pixels
one is aliasing we'll come back to this
later
but when you have square pixels that
line up perfectly
like this you end up getting a lot of
jagged edges
if a line's coming through like that
you'll get this pixel black
this pixel black and then maybe white
and white and you get a jagged edge
with these hex pixels you're more likely
to get a softer
edge the other cool thing about hex
pixels is you get some free
um rotations with our
square pixels i can rotate my image 90
degrees
180 or or 90 in the other direction
just by rearranging what way i draw it i
don't have to resample or recalculate
anything
with so i get i get three free
transformations with a square pixel
with the hex pixel i get five so in some
systems where
you wanted to do rotations um without
losing any data
especially in the old days hex pixels
were your go-to because you got these
free transformations
don't worry too much about it the reason
i'm explaining these to you
is that so you're familiar with the idea
and you might come across it i've seen
i've seen this hex pop up in some
printing contexts in some 3d printing
contexts
and in old hardware specialized hardware
like wearables
but you won't do that in this course
okay we're gonna stick to
our friendly neighborhood square pixels
okay but i wanted to talk about those
all right so these are pixels if we're
dealing with pixels we're dealing with
something called
raster graphics
raster graphics um
[Music]
is a really cool sounding word that's
actually really boring
a raster graphic is nothing more
than a graphic that's made up of a grid
of pixels
that's it it's a raster hey look i'm
drawing your your very first raster
yay okay so raster graphics
are just these grids if i have square
pixels my raster square but i could have
raster with
hex shape and or anamorphic or whatever
as well
so a raster graphics is just this you
have this grid of pixels and each pixel
has a color i have a green green green
you can imagine
um i could make a yellow pixel here i
could do whatever color i want
and you can make shapes by it's kind of
like coloring it on graph paper right
you can make shapes just by coloring the
pixels on your raster
raster graphics are perhaps right now
one of the most popular forms of
graphics in the world
if you've ever used a jpeg file
a png file
i figured what jpeg stands for
joint picture something group png is
portable network graphics
i won't get into the details of
different formats that's more of an
image processing course
but feel free to ask me if you're
curious uh tiff you might have come
across
old days you would have seen bitmaps
bmps
there's old pcx's blah blah blah all of
these
are variations on the raster graphics
format
jpeg uses fourier type compression
bmp is no compression png is lossless
compression doesn't lose any detail
this tiff is made more for cameras and
more for printing
they have all their features but the at
the bottom all that these formats do
is give you a grid of pixels okay
so i'm going to go back to my slides for
a second
um yeah so here we go right this is this
is a raster
raster graphics bam so grid you put
pixels in i'm also going to show this
one
and i'll come back to this again um a
little later
this is a raster graphic i have this
nice smooth looking leaf
if you zoom in it's just a grid in fact
i recommend you try doing that with your
paint your favorite paint tool you zoom
in you zoom in you zoom in
and you should see these square blocks
now these days
some of the programs try to be clever
and they don't show you the square
blocks anymore
they try to make them fuzzy make them
look really nice well
um that might look nice but it doesn't
help
it doesn't help us try to understand her
raster graphics work
okay let's go back
hold on maybe now's a good time to stop
and take a break
so i'll stop this video here and i'm
going to continue
um with this topic um let me come back
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