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8/2/2019 A Vernacular of File Formats
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A Vernacularof
File Formats
8/2/2019 A Vernacular of File Formats
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Define Your Terms(or: Kanye West Fucked Up My Show)
8/2/2019 A Vernacular of File Formats
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Define Your Terms(or: Kanye West Fucked Up My Show)
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Define Your Terms(or: Kanye West Fucked Up My Show)
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Define Your Terms(or: Kanye West Fucked Up My Show)
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Header: the data placed at the beginning of a block of data (in this case the image)
being stored or transmitted.
interleaved vs non-interleavedThe interleaved raw format stores its RGB data
rgbrgbrgbrgbrgbrgbrgbrgbrgb
A planar (non-interleaved) format stores its data:
rrrrrrrrrgggggggggbbbbbbbbb
Photoshop RAWflat binary (header = 0)
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Photoshop RAWflat binary (header = 0)
A channel is the grayscale image of the same size as a color image, made of just
one of these primary colors. For instance, an image from a standard digital camera
will have a red, green and blue channel. A grayscale image has just one channel.
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BMP
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BMP (16)
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BMP (32)
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GIF(1bit color depth)
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GIF(1bit color depth, non-interlaced - 2f replaced for c0)
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GIF(1bit color depth, interlaced)
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GIF(8bit color depth, interlaced - 2f replaced for c0)
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GIF(8bit color depth, interlaced - 2f replaced for c0)
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PNG(8bit color depth, interlaced - 2f replaced for c0)
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PNG(24 bits)
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TARGA
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TARGA(C replaced for F5)
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TIFF(ZIP, Interleaved - m substituted for r)
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PSD
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A JPG compression consists of 6 subsequent steps:
1. Color space transformation
2. Downsampling
3. Block splitting
4. Discrete cosine transform
5. Quantization6. Entropy coding
LOSSY: JPG
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1. Initially, images have to be transformed from the RGB color space to
another color space (called YCbCr), Here the Y refers to the luma or
brightness and the Cb and Cr values stand for the chroma or color
values for the blue and the red channel.
2. Because the human eye doesnt perceives small differences within the
Cb and Cr space very well, these elements are downsampled.
3. After the color space transformation, the image is split into tiles or
macroblocks. Rectangular regions of the image that are transformed and
encoded separately.
4. Next, a Discrete Cosine Transform (which works similar to the
Fourier Transform function, exploited in datamoshing and macroblock
studies) is used to create a frequency spectrum, to transform the
88 blocks to a combination of the 64 two-dimensional DCT basis
functions or patterns (as differentiated by the red lines).
5. During the Quantization step, the highest brightness-frequency
variations become a base line (or 0-value), while small positive and
negative frequency differentiations get a value, which take many fewer
bits to represent.
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JPG(progressive)
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JPG(Baseline standard)
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JPG(baseline optimized)
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The JPEG 2000 standard was mainly developed because of the many
edge and blocking artifacts of the JPG format. JPEG 2000 has
improved scalability and edit-ability.In JPG 2000, after the color transformation step, the image is split into
so-called tiles, rectangular regions of the image that are transformed and
encoded separately.
Tiles can be any size, and it is also possible to consider the whole
image as one single tile. This results into a collection of sub-bands
which represent several approximation scales.
JPG 2000
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