What are Pixel-Based Graphics and How Do They Work?

Pixel-based graphics is a term used to describe a type of digital image that is made up of individual pixels, or tiny dots of color, arranged in a grid-like pattern. These images are commonly used in digital art, video games, and other forms of digital media. The term “pixel” comes from the combination of “picture” and “element,” and refers to the smallest unit of an image that can be displayed on a screen. Pixel-based graphics are created using software that allows artists to manipulate individual pixels to create images with a high level of detail and precision. In this article, we will explore the world of pixel-based graphics and learn how they work.

What are Pixel-Based Graphics?

Definition and Explanation

Pixel-based graphics refer to digital images that are created and displayed using individual pixels, or picture elements. These pixels are the smallest units of digital image that can be displayed on a screen, and they are typically arranged in a grid-like pattern. The number of pixels in an image determines its resolution, which refers to the level of detail and clarity of the image.

Pixel-based graphics are commonly used in digital art, graphic design, and video games, among other applications. They are often created using specialized software, such as Adobe Photoshop or Illustrator, which allows artists and designers to manipulate individual pixels to create complex images.

Pixel-based graphics are also used in various other digital media, such as movies, TV shows, and web content. In these cases, the pixels are typically arranged in a series of frames, which are displayed at a rapid rate to create the illusion of motion.

Overall, pixel-based graphics are a fundamental aspect of modern digital media, and they play a critical role in shaping the way that we experience and interact with digital content.

Advantages and Disadvantages

Advantages:

• Pixel-based graphics are highly detailed and can produce realistic images.
• They can be easily manipulated and scaled to different sizes without losing quality.
• Pixel-based graphics are versatile and can be used in various applications such as websites, video games, and advertisements.

Disadvantages:

• Pixel-based graphics can be time-consuming to create, especially for complex images.
• They require a lot of storage space, especially when working with high-resolution images.
• Pixel-based graphics may not be suitable for small screens or low-resolution devices, as they can appear pixelated and blurry.

Types of Pixel-Based Graphics

Pixel-based graphics refer to digital images that are created by arranging tiny colored squares, known as pixels, in a grid-like pattern. These images are commonly used in digital media, such as websites, video games, and mobile applications. There are several types of pixel-based graphics, each with its own unique characteristics and uses.

1. Raster Graphics:
   Raster graphics, also known as bitmap graphics, are made up of pixels arranged in a grid. Each pixel has a specific color and location, which gives raster graphics a resolution-dependent appearance. They are commonly used for images that require a high level of detail, such as photographs.
2. Vector Graphics:
   Vector graphics are created using mathematical equations, rather than pixels. This means that vector graphics can be scaled to any size without losing quality. They are commonly used for logos, icons, and other graphics that need to be resized frequently.
3. Bitmap Graphics:
   Bitmap graphics, also known as raster graphics, are made up of pixels arranged in a grid. Each pixel has a specific color and location, which gives bitmap graphics a resolution-dependent appearance. They are commonly used for images that require a high level of detail, such as photographs.
4. Pixel Art:
   Pixel art is a type of pixel-based graphics that is created by arranging pixels in a grid to form images. Pixel art is commonly used in video games, animations, and other digital media. It is known for its unique style, which is characterized by small, individual pixels that create a distinct visual effect.
5. 3D Graphics:
   3D graphics are a type of pixel-based graphics that are created by using mathematical algorithms to generate three-dimensional images. They are commonly used in video games, movies, and other digital media to create realistic environments and characters.

Overall, pixel-based graphics are an essential part of modern digital media, and there are many different types of pixel-based graphics, each with its own unique characteristics and uses.

How Do Pixel-Based Graphics Work?

Pixel Structure and Composition

Pixel-based graphics, also known as raster graphics, are digital images composed of pixels, which are tiny dots of color that form the building blocks of the image. The structure and composition of these pixels are critical to the quality and appearance of the final image.

Each pixel in a raster graphic is composed of three primary colors: red, green, and blue (RGB). By combining these colors in different intensities, a wide range of colors can be created. The intensity of each color is measured in bits, with 8 bits per color representing the highest quality and a total of 24 bits for the full color spectrum.

The structure of a pixel is typically a square, and its size is determined by the resolution of the image. The resolution refers to the number of pixels used to create the image, and it is measured in pixels per inch (PPI) or dots per inch (DPI). A higher resolution means more pixels, resulting in a sharper and more detailed image.

When creating pixel-based graphics, it is essential to consider the desired resolution and the number of colors required for the image. The image must be saved in a file format that supports the desired color depth and resolution, such as the Portable Network Graphics (PNG) or Joint Photographic Experts Group (JPEG) format.

Pixel-based graphics are commonly used in digital imaging, web design, and graphic design applications, and they are particularly well-suited for photographs and complex images with a lot of detail. By understanding the structure and composition of pixels, graphic designers can create high-quality images that are optimized for various media and purposes.

Color Depth and Resolution

Pixel-based graphics rely on the concept of color depth and resolution to create images. Color depth refers to the number of colors that can be displayed on a screen, while resolution refers to the number of pixels that make up an image.

The color depth of an image is typically measured in bits per pixel (bpp). A higher color depth means that more colors can be displayed, resulting in more vibrant and realistic images. Most modern displays have a color depth of 24-bits per pixel, which allows for 16 million different colors to be displayed.

Resolution, on the other hand, is measured in pixels per inch (PPI) or dots per inch (DPI). The higher the resolution, the more detailed and sharp an image will appear. For example, a display with a resolution of 1920×1080 pixels will have more pixels than a display with a resolution of 1280×720 pixels, resulting in a sharper and more detailed image.

It’s important to note that while a higher color depth and resolution can result in better image quality, they also require more processing power and memory to render. As a result, older computers may struggle to display images with high color depths and resolutions.

Overall, color depth and resolution are critical factors in the creation of pixel-based graphics. By understanding these concepts, designers and developers can create images that are more vibrant, detailed, and realistic.

Displaying Pixel-Based Graphics

Pixel-based graphics, also known as raster graphics, are made up of pixels, which are small dots of color that come together to form an image. When it comes to displaying pixel-based graphics, there are a few key things to keep in mind.

First, it’s important to have a high-resolution display. This means that the display has a high number of pixels, which allows for more detailed and crisp images. High-resolution displays are typically found in modern devices such as smartphones, tablets, and high-end computers.

Another important factor in displaying pixel-based graphics is the color depth. Color depth refers to the number of colors that can be displayed on the screen at once. A higher color depth means that more colors can be displayed, resulting in a more vibrant and realistic image.

Additionally, the quality of the display itself can impact the way pixel-based graphics are displayed. A high-quality display will have better contrast and color accuracy, which can make a big difference in how the image looks.

Finally, the way the image is scaled can also impact how pixel-based graphics are displayed. If an image is scaled up, it may lose some of its detail and become blurry. On the other hand, if an image is scaled down, it may become pixelated and lose its smoothness.

Overall, displaying pixel-based graphics requires a high-resolution display with a high color depth, a high-quality display, and careful consideration of the scaling of the image. By taking these factors into account, it’s possible to ensure that pixel-based graphics are displayed in the best possible way.

Scaling and Interpolation

Scaling and interpolation are two key techniques used in pixel-based graphics to manipulate and enhance images. These techniques work by altering the size, position, and appearance of pixels in an image, allowing for greater control over the visual quality and resolution of the graphics.

Scaling

Scaling is the process of changing the size of an image while maintaining its aspect ratio. This technique is used to either enlarge or reduce the dimensions of an image, allowing it to fit better on different devices or platforms. There are two main types of scaling:

1. Nearest Neighbor: In this method, the image is scaled by simply repeating pixels from the original image. This results in a blocky appearance, but it preserves the original image’s sharp edges and can be useful for pixel art or low-resolution graphics.
2. Bicubic: This method uses interpolation to estimate pixel values based on neighboring pixels. It produces smoother results than nearest neighbor scaling, making it more suitable for high-resolution images and photographs.

Interpolation

Interpolation is the process of estimating missing pixel values in an image based on the surrounding pixels. This technique is used to smooth out images and reduce noise, resulting in a higher visual quality. There are two main types of interpolation:

1. Bilinear: In this method, pixel values are interpolated using a linear function based on the surrounding pixels. This results in smooth, gradient-like transitions between pixels, making it suitable for photographs and other continuous-tone images.
2. Trilinear: This method extends the bilinear interpolation technique to include an alpha channel, allowing for more accurate color blending between pixels. This is particularly useful for animations and graphics with transparent elements.

In summary, scaling and interpolation are essential techniques in pixel-based graphics that allow for greater control over image size, resolution, and visual quality. These techniques help ensure that images appear sharp, smooth, and visually appealing, regardless of the device or platform they are displayed on.

Common Uses of Pixel-Based Graphics

Pixel-based graphics are images that are created by arranging tiny dots of color, known as pixels, in a grid-like pattern. These images are commonly used in digital media, such as on websites, in video games, and in digital art.

One of the most common uses of pixel-based graphics is in the creation of logos. Logos are often created using pixel-based graphics because they allow for precise control over the color and placement of each pixel, making it easy to create detailed and complex designs.

Another common use of pixel-based graphics is in the creation of user interfaces for websites and applications. Pixel-based graphics are often used for buttons, icons, and other UI elements because they can be easily resized and repositioned without losing quality.

Pixel-based graphics are also commonly used in video games to create characters, backgrounds, and other visual elements. This is because pixel-based graphics allow for the creation of detailed and complex visuals that can be easily animated and manipulated.

Finally, pixel-based graphics are often used in digital art to create surreal, abstract, and other experimental works. Pixel-based graphics allow artists to create intricate patterns and designs using only small dots of color, making it possible to create detailed and intricate images using only a limited color palette.

Pixel-Based Graphics in Modern Technology

Pixel-based graphics refer to the creation and manipulation of images using individual pixels, or picture elements. These graphics are created by arranging pixels in a grid to form an image, with each pixel representing a small area of the overall image. In modern technology, pixel-based graphics are used in a wide range of applications, including computer graphics, video games, and digital imaging.

One of the key benefits of pixel-based graphics is their versatility. Because they are created using individual pixels, they can be scaled up or down without losing any image quality. This makes them ideal for use in a variety of contexts, from small mobile screens to large monitors and televisions.

Another advantage of pixel-based graphics is their ability to create highly detailed images. Because each pixel can be controlled independently, it is possible to create complex images with a high level of detail and resolution. This makes them well-suited for applications such as digital art and photography, where high levels of detail are often required.

In addition to their use in traditional computer graphics and digital imaging, pixel-based graphics are also used in a variety of other modern technologies. For example, they are used in the creation of 3D graphics for video games and other interactive applications, as well as in the development of virtual reality and augmented reality experiences.

Overall, pixel-based graphics play a crucial role in modern technology, providing a flexible and versatile way to create and manipulate images. Whether used in traditional computer graphics, digital art, or cutting-edge technologies like virtual reality, pixel-based graphics continue to be an essential tool for visual communication and expression.

Creating Pixel-Based Graphics

Software and Tools for Pixel Art

There are several software and tools available for creating pixel art, each with its own unique features and capabilities. Some of the most popular options include:

Aseprite

Aseprite is a free, open-source pixel art software that allows artists to create and edit sprites and animations. It features a simple and intuitive interface, as well as a wide range of tools for manipulating and editing pixel art. Some of its key features include:

• Multiple layers for organizing and editing artwork
• Onion skinning for creating smooth animations
• Support for a variety of image formats, including PNG and JPG
• Built-in image editing tools, such as filters and brushes

Piskel

Piskel is another free, open-source pixel art software that is designed to be easy to use and accessible to artists of all skill levels. It offers a range of tools for creating and editing sprites and animations, including a powerful color picker, onion skinning, and support for multiple layers. Some of its key features include:

• Simple and intuitive interface
• Support for multiple platforms, including Windows, Mac, and Linux
• Integration with other software, such as Adobe Photoshop and GIMP

Pixelmator

Pixelmator is a paid pixel art software that offers a range of advanced features and capabilities for creating and editing pixel art. It offers a powerful set of tools for manipulating and editing images, including layers, blending modes, and filters. Some of its key features include:

• Advanced image editing tools, such as filters and effects

Other options

There are many other software and tools available for creating pixel art, including Pyxel Edit, GraphicsGale, and Toontastic. Each offers its own unique set of features and capabilities, so it’s important to choose the one that best fits your needs and preferences.

Techniques and Tips for Pixel Art Creation

Pixel art creation involves using small squares, or pixels, to create images. To achieve the desired outcome, artists use various techniques and tips.

One of the essential techniques for pixel art creation is using the right colors. This involves selecting colors that are opposite each other on the color wheel, as this creates a contrast that makes the image more appealing. Additionally, limiting the number of colors used in the image helps to maintain consistency and coherence.

Another important tip is to use transparency effectively. Transparency allows artists to create a more realistic effect by allowing them to control the opacity of individual pixels. This technique is particularly useful when creating animations or special effects.

To ensure that the image looks good at different sizes, it is important to use a grid when creating pixel art. A grid helps to maintain a consistent spacing between pixels, making it easier to create detailed images that look good at any size.

Another helpful tip is to use the concept of “dithering.” Dithering involves using a limited number of colors to create the illusion of shading and gradients. This technique is particularly useful when working with a small color palette.

Finally, it is important to pay attention to the overall composition of the image. This involves considering the placement of elements within the image, as well as the overall balance and contrast. By paying attention to these factors, artists can create pixel art that is visually appealing and engaging.

Common Mistakes to Avoid in Pixel Art

When creating pixel art, there are several common mistakes that one should avoid to ensure that the final result is of high quality. Some of these mistakes include:

• Not using reference images: One of the most common mistakes in pixel art is not using reference images. Reference images can help ensure that the artist is creating an accurate representation of the subject matter.
• Poor color choices: Choosing poor colors can make the pixel art look unprofessional. It’s important to choose colors that complement each other and the subject matter.
• Using too many colors: Using too many colors can make the pixel art look cluttered and unprofessional. It’s important to use a limited color palette to ensure that the pixel art looks clean and professional.
• Lack of attention to detail: Pixel art requires a lot of attention to detail. One mistake can ruin the entire piece. It’s important to take the time to ensure that each pixel is placed correctly.
• Ignoring the rule of thirds: The rule of thirds is an important principle in art. It states that an image should be divided into thirds, both horizontally and vertically, and the key elements of the image should be placed at the intersections or along the lines. Ignoring this rule can make the pixel art look unbalanced and unprofessional.
• Poor composition: Composition is an important aspect of pixel art. It’s important to consider the placement of the subject matter and the use of negative space to create a visually pleasing piece.
• Lack of contrast: Contrast is important in pixel art to create depth and dimension. It’s important to ensure that there is enough contrast between the subject matter and the background.

By avoiding these common mistakes, one can create high-quality pixel art that is visually pleasing and professional.

Pixel Art for Different Platforms and Devices

Pixel art is a type of digital art that is created by using small, individual pixels to form images. This art form has been around since the early days of computer graphics and has become increasingly popular in recent years due to the rise of mobile gaming and the popularity of retro-style graphics.

One of the key advantages of pixel art is its versatility. It can be used on a wide range of platforms and devices, from traditional desktop computers to mobile phones and tablets. In fact, pixel art is often used in mobile games because it is well-suited to small screens and low-power devices.

In order to create pixel art for different platforms and devices, it is important to consider the resolution and pixel density of the target device. For example, a pixel art image that is intended for a high-resolution desktop monitor will need to be much larger than an image intended for a low-resolution mobile phone screen.

Additionally, some platforms and devices may have specific requirements for pixel art, such as certain color palettes or file formats. For example, some mobile games may require pixel art to be created in a specific file format in order to work properly on the device.

Overall, creating pixel art for different platforms and devices requires a careful consideration of the target platform’s specifications and requirements. By following these guidelines, artists can create high-quality pixel art that looks great on a wide range of devices.

Pixel-Based Graphics and User Experience

Human Perception and Pixel-Based Graphics

Pixel-based graphics, also known as raster graphics, are images that are created by arranging pixels, or tiny dots of color, in a grid. The resolution of a pixel-based graphic refers to the number of pixels used to create the image, and the higher the resolution, the more detailed and sharp the image will appear.

The human eye is capable of perceiving a wide range of colors and tones, and pixel-based graphics are designed to take advantage of this by using a large number of colors and shades to create a highly realistic image. However, the perception of pixel-based graphics is not limited to the eye alone. The brain also plays a role in how we perceive these images, and it is able to fill in gaps in the image and smooth out areas of low resolution to create a more complete picture.

This ability of the brain to fill in gaps and smooth out areas of low resolution is known as the “halo effect.” It allows pixel-based graphics to appear more realistic and smooth, even at lower resolutions. However, if the resolution is too low, the halo effect will not be able to compensate for the lack of detail, and the image will appear blurry and indistinct.

Therefore, the resolution of pixel-based graphics is a crucial factor in determining the quality of the image and the user experience. Higher resolutions will result in more detailed and sharp images, while lower resolutions will result in less detailed and less realistic images. The halo effect can help to improve the appearance of pixel-based graphics at lower resolutions, but it has its limits, and the user experience will ultimately depend on the resolution of the image.

Impact of Pixel-Based Graphics on User Experience

Pixel-based graphics, also known as raster graphics, have a significant impact on user experience. These graphics are created by arranging pixels in a grid, where each pixel represents a color and brightness value. The arrangement of these pixels determines the overall visual appearance of an image or graphic.

Here are some ways in which pixel-based graphics can impact user experience:

1. Visual Appeal: Pixel-based graphics can be used to create visually appealing images and graphics that can enhance the overall user experience. For example, they can be used to create eye-catching buttons, icons, and other visual elements that can make a website or application more engaging.
2. Responsiveness: Pixel-based graphics can be designed to be responsive, meaning they can adapt to different screen sizes and resolutions. This can ensure that graphics look good on a variety of devices, from small smartphones to large desktop monitors.
3. Interactivity: Pixel-based graphics can be used to create interactive elements, such as animations and interactive maps. This can help to create a more engaging and dynamic user experience.
4. Brand Identity: Pixel-based graphics can be used to create a consistent brand identity across different platforms and media. This can help to establish a strong brand image and make a company more recognizable to customers.
5. Accessibility: Pixel-based graphics can be designed to be accessible to users with different abilities and needs. For example, they can be designed to be easily readable for users with visual impairments, or they can be made larger or smaller to accommodate users with different screen sizes.

Overall, pixel-based graphics can have a significant impact on user experience. By using high-quality, visually appealing graphics, designers can create a more engaging and interactive user experience that can help to build brand loyalty and increase customer satisfaction.

Pixel-Based Graphics and Accessibility

Pixel-based graphics are a type of digital image that is made up of individual pixels, or small dots of color, arranged in a grid. These graphics are commonly used in web design, video games, and other digital media.

When it comes to accessibility, pixel-based graphics can present a challenge for users with visual impairments. This is because the small size of the pixels can make it difficult for these users to distinguish between different elements on the screen.

To address this issue, designers can use a number of different techniques to make pixel-based graphics more accessible. One approach is to use larger pixels or a larger grid size, which can make it easier for users to see and navigate the elements on the screen. Another approach is to use high-contrast colors, which can help users with low vision more easily distinguish between different elements.

Another important consideration for accessibility is the use of alt text. Alt text is a brief description of an image that is provided for users who are unable to see the image. This can include users with visual impairments, as well as users who are using screen readers to access the content. By providing clear and concise alt text for pixel-based graphics, designers can ensure that all users can understand and engage with the content.

Overall, designers can improve the accessibility of pixel-based graphics by using larger pixels, high-contrast colors, and alt text. By taking these steps, designers can ensure that all users can access and engage with the content, regardless of their visual abilities.

Future of Pixel-Based Graphics and User Experience

The future of pixel-based graphics and user experience is a fascinating topic to explore. As technology continues to advance, it is likely that pixel-based graphics will become even more sophisticated and integrated into our daily lives.

Increased Realism and Immersion

One of the key trends in the future of pixel-based graphics is the increased realism and immersion that they will provide. As graphics processing units (GPUs) become more powerful, it will be possible to create images that are indistinguishable from reality. This will enable developers to create immersive experiences that will transport users to entirely new worlds.

Augmented Reality and Virtual Reality

Another area where pixel-based graphics are likely to have a significant impact is in augmented reality (AR) and virtual reality (VR) applications. As AR and VR technologies become more widespread, it is likely that pixel-based graphics will play a key role in creating realistic and engaging experiences. This could include everything from gaming to education and training.

Increased Integration with AI

As artificial intelligence (AI) continues to advance, it is likely that pixel-based graphics will become even more integrated with this technology. This could include using AI to create more realistic and responsive characters in games, or to generate entirely new types of graphics that are based on machine learning algorithms.

Accessibility and Inclusivity

Finally, as pixel-based graphics continue to evolve, it is important to consider issues of accessibility and inclusivity. This could include making sure that graphics are optimized for users with different abilities, or creating graphics that are culturally sensitive and representative of a diverse range of people.

Overall, the future of pixel-based graphics and user experience is likely to be shaped by a range of different factors, including advances in technology, changes in user behavior, and broader societal trends. As these factors continue to evolve, it will be important to stay attuned to new developments and to think creatively about how pixel-based graphics can be used to enhance the user experience in new and innovative ways.

Recap of Key Points

Pixel-based graphics refer to images that are created by individual pixels, which are the smallest units of digital image that can be displayed on a screen. These graphics are used in a variety of applications, including video games, movies, and websites, to create a wide range of visual effects.

The key to understanding how pixel-based graphics work is to understand how they are created and manipulated. This involves understanding the concept of pixels and how they are arranged on a screen to form images.

In a pixel-based image, each pixel is assigned a color value, which is typically represented as a combination of red, green, and blue (RGB) values. The specific color of each pixel is determined by the intensity of each of these color channels, which can be adjusted to create a wide range of colors.

Once an image has been created, it can be manipulated in a variety of ways to create different visual effects. This can involve changing the color or brightness of individual pixels, or altering the arrangement of pixels to create different shapes and patterns.

One of the key benefits of pixel-based graphics is that they can be scaled up or down without losing quality. This is because the image is made up of individual pixels, which can be adjusted to create the desired visual effect at any size.

Overall, pixel-based graphics are an important part of modern digital media, and understanding how they work is essential for anyone who wants to create high-quality visual content for a variety of applications.

Final Thoughts and Recommendations

In conclusion, pixel-based graphics play a crucial role in enhancing the user experience of digital devices. The technology behind these graphics involves a complex process of manipulating pixels to create images and videos that are visually appealing and realistic. By understanding the science behind pixel-based graphics, designers and developers can create more effective and engaging digital content.

That being said, it is important to consider the limitations of pixel-based graphics. As the technology continues to advance, there may be a tendency to prioritize aesthetics over functionality. This could lead to the creation of visually stunning content that fails to meet the needs of users. Therefore, it is essential to strike a balance between aesthetics and functionality when designing and developing digital content.

One way to achieve this balance is to focus on creating content that is both visually appealing and easy to use. This involves understanding the needs and preferences of users and designing content that is intuitive and user-friendly. By prioritizing user experience, designers and developers can create content that is both visually appealing and functional.

Another recommendation is to stay up-to-date with the latest advancements in pixel-based graphics technology. This involves staying informed about new software and tools that can help improve the quality and effectiveness of digital content. By staying current with the latest technology, designers and developers can create content that is both visually appealing and technically advanced.

In summary, pixel-based graphics play a vital role in enhancing the user experience of digital devices. To create effective and engaging content, it is important to strike a balance between aesthetics and functionality, prioritize user experience, and stay up-to-date with the latest advancements in technology. By following these recommendations, designers and developers can create digital content that meets the needs and preferences of users.

FAQs

1. What are pixel-based graphics?

Pixel-based graphics are digital images that are created using pixels, which are the smallest units of digital image that can be displayed on a screen. Pixel-based graphics are commonly used in digital media, such as websites, videos, and computer games.

2. How are pixel-based graphics created?

Pixel-based graphics are created by arranging individual pixels in a grid to form an image. The pixels are typically arranged in rows and columns, and each pixel is assigned a color value. The color values of the pixels are then combined to create the final image.

3. What are the advantages of using pixel-based graphics?

One advantage of using pixel-based graphics is that they can be scaled up or down without losing image quality. This makes them ideal for use on websites and other digital media where the image size may need to be adjusted. Additionally, pixel-based graphics can be created using a wide range of software tools, making them accessible to designers with different levels of expertise.

4. What are some common uses for pixel-based graphics?

Pixel-based graphics are commonly used in website design, video game design, and digital advertising. They can be used to create logos, buttons, icons, and other graphical elements that are used to enhance the visual appeal of digital media.

5. Can pixel-based graphics be used in print media?

Pixel-based graphics can be used in print media, but they may not produce the best results. This is because pixel-based graphics are optimized for digital screens, and the quality of the image may be reduced when it is printed. It is generally recommended to use vector-based graphics for print media.

What is Pixel? – How Computer Understands an Image?