TIFF “Tag Image File Format”

Posted by vuit_admin on Thursday, March 27, 2014 in Uncategorized .

What is a TIFF?

Originally designed as a common binary image format for desktop scanners, TIFF gradually evolved to become one of the most widely used formats for storing bit-mapped images such as digital photographs and line art graphics. It is one of the three popular formats (along with JPEG and PNG) suitable for representing multi-color images. TIFF graphics can also be black and white or gray-scaled.

What makes the TIFF image format so special?
The TIFF image file format is based on the lossless compression method, allowing for an image to be stored without losing even a percent of its original data. Moreover, an image in TIFF format can undergo multiple edits with no negative effect on its quality parameters. This makes it preferable over the flexible but 'lossy' JPEG file format. TIFF also gives users the option to choose the LZW compression technique, officially supported by the GIF image format. This technique is characterized by allowing decrease of the image file's size with the data compression execution.

The TIFF file format offers a high level of flexibility, giving users the chance to handle images and data within a single file. This is done with the help of the image structuring header tags such as size, definition, applied image compression, data arrangement that are included in the TIFF file.

An example of such a file, is a TIFF that stores compressed JPEG and RLE images or a vector-based clipping path, containing cropping, outlines, image frames, etc.

TIFF format specifications?
The TIFF format reproduces images' color configuration by using 32bit offsets. This defines a limitation on the size of a TIFF file of 4 GB. Files in TIFF format are usually recognized by their .tif extension.

Thanks to its rich set of advantages in color images reproduction, TIFF is supported by the majority of image manipulation software, publishing, page layout applications and word processors. Moreover, it is a preferred image format for a wide range of scanning, faxing and OCR (optical character recognition) tools.

Although being in use for a long time now, TIFF has not had a major update for at least 15 years. This may well be attributed to the persistently high levels of efficiency and stability shown by the TIFF 6.0 specification released back in June 3, 1992. For that period the format has only been added to some minor extensions/ specifications such as TIFF/EP – a digital image file format standard.

Image file formats – Advantages and Disadvantages

A simple table i wrote a while ago on different file formats for image storage and their advantages and disadvantages. I hope people may find it useful!

File Format	Advantages	Disadvantages
JPG	Small File Size – Ideal for web use and email. Varying rates of compression reduce file size further, at a cost of loss of original image quality Recognised file format on all computers as well as displaying on digital photo frames, mobile phones, DVD players etc. Ideal for small prints such as instant photo booths. Can embed colour space profiles as well as ITPC Metadata	Lossy compression, as the file is compressed to save space, it loses some of the original file data and therefore degrades image quality Further editing on the image can degrade quality even further. Only suitable for smaller print output, as on larger images, compression artefacts and noise can be present on final print.
TIFF	Uncompressed image retains maximum amount of image data from the camera. Can be compressed to reduce file sizes using mathematical algorithms such as ZIP or TAR without loss of image data Can also use lossy compression such as JPG algorithms to reduce file size Recognised format by most computers, cross compatible with both MAC and PC’s Standard format for printing either at home or dedicated Photo lab. Can embed colour space profiles as well as ITPC Metadata	Large file sizes, around 20mb for a 10 megapixel image, so larger storages devices needed for long term archival use. Good specification computer needed to process and load images. Most website and online images galleries do not support tiff uploading. Slow speeds when transferring to online galleries that do support TIFF files
PSD	A format created by Adobe for Photoshop use, it contains all the original image data as well as any layers, adjustments and full image history. Ideal for use when processing images as a user can save the file and then go back to it at a later date	Generally only recognised by Photoshop software and certain other image manipulation software
Camera RAW	Uncompressed image, direct from camera sensor Best image quality overall as well as flexibility in post processing Things such as white balance, exposure, colour space, contrast, saturation can all be adjusted by software easily It is a non destructive format, therefore any changes made such as cropping or adjustments can be undone and the image reverted back to its original state. Can embed colour space profiles as well as ITPC Metadata	Needs dedicated RAW converter to process images such as Adobe RAW or Cameras own software Good specification computer needed to process and load images. Most website and online images galleries do not support RAW uploading. Not recommended for use when sending to printing labs or similar due to incompatibilities and the nature of the file type. Large file sizes, approx 12mb for a 10 megapixel file.
Adobe Digital Negative	Similar camera RAW, created by Adobe as a standardised format Uncompressed image, identical to original Camera RAW file Best image quality overall as well as flexibility in post processing Things such as white balance, exposure, colour space, contrast, saturation can all be adjusted by software easily It is a non destructive format, therefore any changes made such as cropping or adjustments can be undone and the image reverted back to its original state. Slightly smaller file sizes compared to Camera RAW, approximately 8mb for a 10 Megapixel image Cross compatible with all Adobe software so no additional RAW converter needed Can embed colour space profiles as well as ITPC Metadata	Needs Adobe Software or compatible to open and process image Good specification computer needed to process and load images. Most website and online images galleries do not support Adobe Digital Negative uploading. Not recommended for use when sending to printing labs or similar due to incompatibilities and the nature of the file type. Large file sizes, approx 8mb for a 10 megapixel file.

Code		Name	Short description
Dec	Hex	Name	Short description
254	00FE	NewSubfileType	A general indication of the kind of data contained in this subfile.
255	00FF	SubfileType	A general indication of the kind of data contained in this subfile.
256	0100	ImageWidth	The number of columns in the image, i.e., the number of pixels per row.
257	0101	ImageLength	The number of rows of pixels in the image.
258	0102	BitsPerSample	Number of bits per component.
259	0103	Compression	Compression scheme used on the image data.
262	0106	PhotometricInterpretation	The color space of the image data.
263	0107	Threshholding	For black and white TIFF files that represent shades of gray, the technique used to convert from gray to black and white pixels.
264	0108	CellWidth	The width of the dithering or halftoning matrix used to create a dithered or halftoned bilevel file.
265	0109	CellLength	The length of the dithering or halftoning matrix used to create a dithered or halftoned bilevel file.
266	010A	FillOrder	The logical order of bits within a byte.
270	010E	ImageDescription	A string that describes the subject of the image.
271	010F	Make	The scanner manufacturer.
272	0110	Model	The scanner model name or number.
273	0111	StripOffsets	For each strip, the byte offset of that strip.
274	0112	Orientation	The orientation of the image with respect to the rows and columns.
277	0115	SamplesPerPixel	The number of components per pixel.
278	0116	RowsPerStrip	The number of rows per strip.
279	0117	StripByteCounts	For each strip, the number of bytes in the strip after compression.
280	0118	MinSampleValue	The minimum component value used.
281	0119	MaxSampleValue	The maximum component value used.
282	011A	XResolution	The number of pixels per ResolutionUnit in the ImageWidth direction.
283	011B	YResolution	The number of pixels per ResolutionUnit in the ImageLength direction.
284	011C	PlanarConfiguration	How the components of each pixel are stored.
288	0120	FreeOffsets	For each string of contiguous unused bytes in a TIFF file, the byte offset of the string.
289	0121	FreeByteCounts	For each string of contiguous unused bytes in a TIFF file, the number of bytes in the string.
290	0122	GrayResponseUnit	The precision of the information contained in the GrayResponseCurve.
291	0123	GrayResponseCurve	For grayscale data, the optical density of each possible pixel value.
296	0128	ResolutionUnit	The unit of measurement for XResolution and YResolution.
305	0131	Software	Name and version number of the software package(s) used to create the image.
306	0132	DateTime	Date and time of image creation.
315	013B	Artist	Person who created the image.
316	013C	HostComputer	The computer and/or operating system in use at the time of image creation.
320	0140	ColorMap	A color map for palette color images.
338	0152	ExtraSamples	Description of extra components.
33432	8298	Copyright	Copyright notice.