FrameBuffer

What is Framebuffer?

The term framebuffer refers to the memory of the video card that contains all the necessary information and data for rendering an image on the computer screen.

Technically, this refers to the specific location on the memory that holds the frame of data. It is sent continuously to the screen, so that image is seamlessly displayed. It contains a bitmap, which drives the video display.

Understanding Framebuffer

Understanding Framebuffer

In simple terms, while the resolution in computer graphics signifies the number of pixels, the framebuffer signifies the location of the memory that stores the information and data for those pixels.

Framebuffer, is actually a single word, and is also known by different names such as:

The main objective of the framebuffer is to:

The features of the framebuffer are typically determined by the size and speed of its memory and other primary costs. Some of the most common features of the framebuffer are:

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The images in the framebuffer can also be cleared to a specific value depending on the different states such as:

Framebuffers can be accessed by direct memory mapping to the memory space of the Central Processing Unit (CPU). However, this is not the only method. Some of the other common ways of accessing the framebuffer are:

There may be virtual framebuffers in a few systems for the sake of compatibility such as:

What is the Use of Framebuffer?

A framebuffer is typically used during off-screen rendering and also for a few advanced algorithms that are specifically used for rendering.

Different aspects of the framebuffer also serve specific purposes such as:

The framebuffer can store different objects such as:

However, all of these buffers are not required every time, but the framebuffer will use the color buffer or the depth buffer for rendering always, and sometimes it may use both of these.

Ideally, the depth buffer is not used by the framebuffer if depth testing is disabled, and a few specific types of rendering algorithms, such as shadow mapping, use the depth buffer but no color buffer.

In the modern video cards, the framebuffer circuitry is usually in the cores and it is used to convert an in-memory bitmap into a video signal that can be displayed on the computer screen.

Sometimes, the framebuffer may also be designed specifically with adequate memory space to use it to store video data for two frames.

This is usually done by a process called double buffering or page flipping, where half of the memory of the framebuffer is used to show the existing frame.

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What is Framebuffer Size?

The size of the framebuffer signifies the size of the maximum image displayed and can be a different memory bank on the display adapter or graphics card. It can also be a reserved part of the regular memory.

Ideally, every element in a framebuffer matches the individual size of the pixel on the screen. The intensity of these pixels is determined by the voltage.

The framebuffer traditionally supports a wide range of color modes depending on the extent of memory or its size such as:

The size of the framebuffer determines two specific aspects of the image such as:

It can be minimum or maximum, as is clarified in the following paragraph.

The minimum size of the framebuffer to support rendering an image with the most commonly used screen resolution is 1024 × 768 in 24 bits.

On the other hand, the maximum size of the framebuffer will be 3 x 1310720 = 3932160 bytes if a frame comprises 1280 x 1024 = 1310720 pixels.

Considering both, the typical size of the framebuffer should be 3932160 bytes.

The color values are stored in different sizes and formats and there may also be an extra alpha channel that is used to hold information regarding the transparency of the pixels.

Considering all these contents, the final size of the framebuffer depends on the following:

How Does Framebuffer Affect Image Quality?

Apart from the speed of the graphics card and hardware, the size of the framebuffer typically affects the resolution of the final image displayed.

Ideally, this resolution is defined in terms of two particular numbers as follows:

What is Framebuffer Format?

The framebuffer format is either the actual output displayed on the screen or the image captured as a screenshot. Usually, the standard format for it is ‘Compressed (32 bits)’.

It can be the lower one, such as an 8-bit integer RGBA, which is equal to 32 bits, or the higher Half16, which is usually 4 x 16-bit floats RGBA and is equal to 64 bits.

As said earlier, the buffer typically contains the color values of each pixel to be displayed on the computer monitor. These color values are usually stored in different color formats such as:

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Typically, the framebuffer format helps in different aspects such as:

Framebuffer Vs Pixel Buffer

What is a Framebuffer Driver?

A framebuffer driver refers to the transitional layer.

This layer is typically used to hide the complications of the video device underlying from the space applications of a user.

What Is Framebuffer Depth?

The framebuffer depth refers to the number of bits present in each pixel.

Considering the depth to be 24 and that it contains red, green and blue values, each value will be 8 bits, or 1 byte.

Conclusion

In simple terms, as it is explained in this article, the term framebuffer usually refers to the specific location on the memory where the color data is stored for an image to be exhibited on the computer screen.

These colors of the pixels held by the framebuffer can be reversed to highlight any specific region.