File Formats - Adobe Photoshop

Each Photoshop book I ever picked up had a section on file formats. Each time I browse through one, I m disappointed to realize that they never discuss the formats I use every day in the film/entertainment/movie industry. EPS, one of the most used and arguably important formats for print and advertising, is almost never used in VFX work. Usually the less well-known formats used in the industry have a little blurb(if mentioned at all)that reads “extremely high-end formats used in 3D animation.”

PSD

Of course, the first option on the list of supported file formats is Photoshop’s native format, PSD. you are probably saving your working file as a PSD. This is logical and wise.

This is the first and most common option for saving files in Photoshop.

first and most common option for saving files in Photoshop

Obviously, using Photoshop’s native format makes the program operate more efficiently, and you are assured that it can support every program option, whether it is a vector mask layer, an adjustment layer, or an annotation. In addition, PSD format is generally more efficient at applying lossless ompression to the file than any other format. TIFF can sometimes do better compression, but you give up the ability to save certain Photoshop functions. I go into TIFF in the next section, but first a word on PSD 2.0 format. Ultimately, you probably have to save a flattened version of your image for the pipeline, but are likely to always use PSD in some capacity while working.

TIFF

Arguably the most popular image format, TIFF stands for Tagged Image File Format and can be suffixed as .tiff or .tif. That alone should clue you to the possible problems that can arise. Although well known across the gamut of digital artists, it is misleading to call it a format;TIFFs are an extensible format, which means that others can modify the original specifications. This can lead to incompatibilities with programs that only support the baseline TIFF standard. Photoshop, for example, supports layered TIFFs; you can save something as a TIFF but maintain the layer information. The problem is that other programs can’t see that info. Another example is the 16-bitand 8-bit TIFF. Many programs try to read a 16-bit TIFF as an 8-bit TIFF, which leads to other imaging troubles. Then there is the question of byte order. When in doubt, save using the IBM PC option. Saving in Mac byte order can sometimes cause problems with PCs, but Macs can generally interpret the PC byte order. Nonetheless, the TIFF format is still popular, due to its prior years of being the safest bet on transferring images between platforms and programs and its continued importance in the publishing world. Although more image formats are supported by graphics programs nowadays, most of which are cross platform, TIFFs can be confidently used as long as you specify your bit depth One of TIFF’s advantages are its compression options:

  • LZW and ZIP. Two very common lossless compression formats, where no information is deleted to compress your image.
  • JPEG compression.A lossy compression that compresses into smaller files at the expense of image degradation.

Another TIFF advantage is that it can be up to 4GB in size—a definite boon in the film matte painting world, where the 2GB limit of some other formats can be prohibitive.

TGA

Although the TGA(Targa) format was designed for systems using the Truevision video board, this stable and commonly supported format is always 8 bit. This means that each channel is no more than 8 bits. It is a bit confusing, because the images are referred to as 16-, 24-, and 32-bit images. This means Targa supports these:
16-bit RGB images: 5 bits × 3 color channels + 1 unused bit
24-bit RGB images: 8 bits × 3 color channels
32-bit RGB images: 8 bits × 3 color channels + 1 8-bit alpha channel
File Formats 83

The Targa format also supports indexedcolor and grayscale images without alpha channels. This was the file format of choice in many studios I worked at, including Rhythm & Hues Studios and WETA Digital. However, I think, with Photoshop CS now able to paint in true 16-bit color, that other formats will be used more and more.

PSB(Large Document)

Photoshop’s solution for huge files, PSB is new to Photoshop CS. You must first select the Enable Large Document Format option in your preferences. Most formats have a 2G limit to their file size, but PSB can handle larger files and keep Photoshop features such as layers and filters intact. Of course, as of this writing, Photoshop is the only program that supports this format.

CIN

Developed by Kodak, Cineon, used interchangeably with DPX(Digital Picture Exchange)is a 10-bit-per-channel logarithmic digital format used mostly by compositors. The 10-bit log file emulates 16- or 12-bit images that capture the dynamic range of film. (A 10-bit linear file lacks the range). Of course, this means that saving a matte painting for a compositor will often use this format. Despite increased support for other formats, and with 16-bit per-channel capabilities being more prevalent, this format is used often in transferring film to digital and is still prevalent in the VFX world.

IFF

Most commonly associated with Alias/ Wavefront(or with Amiga, for you old school people), IFF Interchange File format)is a general-purpose data storage format that has extensions that support still picture, sound, music, video, and textual data. Most of the time, however, IFF is for opening a Maya-rendered image or saving an image for use in a Maya pipeline.

Filmstrip

The Filmstrip format is used for RGB animation or movie files created by Adobe Premiere. I haven’t used this format in any of the studios that I have worked at—even the small, boutique shops. Premiere is used by quite a few smaller shops, so I assume quite a few request this format. Photoshop does caution that if you resize, resample, remove alpha channels, or change the color mode or file format of a Filmstrip file in Photoshop, you can’t save it back to Filmstrip format. Kinda makes me wonder if this is useful after all.

3D Programs

3D programs include Wavefront RLA, Alias PIX, Electric Image, SoftImage, 3DStudio Max, or proprietary formats. Just about every 3D program has a Photoshop plug-in that allows you to save an image in its native image format, whether that be RLA, PIX, or 3DS. More often than not, wherever you’re working has a pipeline that optimizes this, and you work with that format because your supervisor tells you so.

SGI RGB

When I was working on UNIX machines, I almost always saved with SGI’s RGB format. It is an 8-bit RGB or grayscale image, and can have the suffix SGI or RGB. The confusion came when someone would say to “Save it out as an SGI,” but expect an RGB suffix. Just in case you are working on UNIX machines, I will reiterate:RGB and SGI are used interchangeably.

PhotoCD

Another format developed by Kodak, the PhotoCD(PCD) format allows five resolutions to be contained in a single file. Often, reference CDs are in this format and you simply read it in and save it as a different format for your use

Pixar

Do you work at Pixar? Then you know this format and know when you are supposed to save this way. Everyone else? You don’t work at Pixar and won’t be using this format.

RAW
Photoshop supports most camera RAW formats. This format not only saves uncompressed image data, but also the image’s metadata. You do not save in this format, but may occasionally use it to import reference or source images. Usually the RAW formats are converted and delivered as TIFFs, but you have to deal with this format if you end up taking the images directly off the camera’s drive. Now here are some of the other available formats that you hear a lot about, but probably will not use in the course ofpainting for special effects.

JPEG

One of the most popular formats almost never used in film or television, the Joint Photographic Experts Group(JPEG) format is very effective at compression and lets you choose the level at which you wish to compress. This format is most commonly used to display photographs and other continuous-tone images over the Internet. A JPEG compresses information by looking at an 8×8 block of pixels and combining similar-color pixels. It is alossy compression, resulting in the irrevocable loss of data—especially apparentafter multiple saves. Because of this, you do not use this format for film.

JPG2000 is the newest rendition of the standard JPG. JPG2000 now has a lossless compression option, supports 16 bit, and has a new feature called ROI for Region of Interest. This allows you to define a region(via alpha channel)that has a lower compression rate than the rest of the picture. Sounds intriguing, but like anything new, there isn’t yet widespread support for this version of JPG. This format is used, however, to show clients, in-progress work, as its compact format is ideal for teleconferences and rough viewing.

GIF

One of three most common formats for the web, the Graphics Interchange Format(GIF)is highly ompressible, but is 256 colors—much too limiting for film work.

EPS

Encapsulated PostScript is a format commonly used in the publishing world. You never use this format, unless, of course, you are getting a file from an advertising or publishing company. Okay, I take that back. If you like to use Adobe Illustrator, this file format allows you to save clipping paths and link it to your Photoshop file rather than embedding the clipping paths. Still, the majority of VFX artists never see this format.

PDF

Adobe Acrobat’s native format, PDF is the acronym for Portable Document Format. Mostly used for documents, it is good for showing someone images because the reader is available for PC, Mac, and UNIX, and is a free download at Adobe’s web site. My supervisor, however, prefers to just come by my desk to see the images.

BMP

The bitmap format(BMP)is the standard Windows graphics file format.

PICT

PICT, short for Macintosh Picture, is the native Mac graphics file format. By now you may be wondering what happened to all the pretty pictures. Didn’t I say I was going to put in as many pictures as possible? Well, my young grasshopper, take a look at Figure below to see some of the differences between the formats.

A taste of the difference between some of the formats; take a look at these close ups of the same picture.

taste of the difference between some of the formats; take a look at these close ups of the same picture

A Word about HDRI

Generally, all of the preceding “normal” formats are low dynamic range images(LDRI). A scene’s dynamic rangeis the contrast ratio between its brightest and darkest parts. A high dynamic range image
(HDRI) is an image made by combining multiple normal images of the same scene taken with different exposure levels; each end-result pixel in an HDRI stores the amount of light in a floating-point number
with no upper limit. Compare this to the RGB image integer values of 0 to 255, and you can imagine the difference.

An HDRI and LDRI at different exposure settings.

HDRI and LDRI at different exposure settings

The beautiful luminance resulting from the use of HDRI is absolutely stunning Unfortunately, as of this writing, working with an HDRI in Photoshop is, at best, convoluted. I can’t wait until a plug-in is released for Photoshop to deal with HDRI


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