Photo Technical

Camera storage and formats: A balancing act between typical file size and image quality -A52

Welcome aboard photo enthusiasts… Going through all the articles I’ve written, covering the list of camera specifications, using the Lumix DMC-FX150 camera, will give you a solid understanding of your pocket camera.  Irrespective of the sample camera used the information discussed is applicable to all pocket cameras.  Remember, this one by Panasonic is no longer current, and there are many terrific options by other manufacturers.

Dwindling down the list, last time we ended with Time-lapse recording. Let’s move on to:

Orientation sensor: yes – When you take a vertical picture the camera will automatically change the orientation to vertical when holding the camera horizontally to preview your shots.  In other words, both horizontal and vertical shots will show in the proper orientation without physically having to rotate the camera horizontally and vertically.  That makes images easier to preview.

Storage types: SD/MMC/SDHC card, Internal – We use to load a roll of film, but now we put in a storage card.  These cards are growing by Gigabytes; 2,4,6,8 and greater, having the ability of taking far more pictures, over a thousand using in the jpg format and by the hundreds if shooting RAW, over a roll of film.  They are smaller than a roll of film making it possible to manufacture smaller cameras, and cost for larger capacity card keeps tumbling down, down, down.

Unfortunately one size does not fit all.  Different cameras can use different memory cards.  There are Compact Flash cards that are a reliable format.  There are microdrives, SmartMedia, Sony Memory Sticks, various forms of Multi Media Cards, xD picture Cards, and other memory formats, but the Secure Digital (SD) seems to be among the most popular. This matters in getting better pricing and having a popular product insures more R&D advances.

 

Storage included: 50 MB Internal – This is not a lot, but a bit of a buffer for a half dozen jpg’s or so without putting in a memory card.

 

Uncompressed format: Yes, RAW – To better understand Raw files it is best to give an overview of how images taken are stored.  Cameras have built in software capable of compressing files.  The purpose of this is to reduce file sizes enabling more photos to be stored on memory disks.  It also allows for faster downloading and transfer of those files, for instance, on the Web.

Lossless compressed TIFF files are an option sometimes provided by cameras in saving photos taken. Lossy compressed jpg’s are another and by far the most popular image filing format.  For this, the software within the camera rearranges information contained in the photo taken and discards what is determined to be unnecessary.

This determination by the software follows the way we see.  All mammals have the Where system of sight.  This is based on luminance levels, and allows us to see spatial arrangements, depth, coarse and to a lesser extend fine detail.  More advanced mammals like humans also developed a What system in seeing colors.

Colors are part of our identification process of objects, but it is not as well or critically defined as the Where system.  Therefore, technically colors can be compressed to a greater degree without our seeing the difference or taking notice.

For example, you may take a photo with a lot of blue sky.  A lot of 0 and 1’s repeat in the digital formula to represent this blue sky.  The camera software determines it can eliminate the repetitions for the blue sky by compressing information representing all that blue, that is, it summarizes aspects of an image.  Of course, once the information has been discarded… it is gone, never to be re-created to its original status.  Again, this reduction by as much as a factor of 20 leaves more memory space is the trade-off of this action.

A reciprocal article on the subject on dpreview.com offers this chart below to show the compression of various image formats.
Image Format Typical File Size in MB Comment
Uncompressed TIFF 14.1 3 channels of 8 bits
Uncompressed 12-bit RAW 7.7 1 channel of 12 bits
Compressed TIFF 6.0 Lossless compression
Compressed 12-bit RAW 4.3 Nearly lossless compression
100% Quality JPEG 2.3 Hard to distinguish from uncompressed
80% Quality JPEG 1.3 Sufficient quality for 4″ x 6″ prints
60% Quality JPEG 0.7 Sufficient quality for websites *
20% Quality JPEG 0.2 Very low image quality

You may have assumed correctly that the camera software automatically determines through its software what to discard…leaving you no control.  This is where RAW comes into play.  With this quality setting files are stored in the cameras native format and nothing is compressed or discarded.

What this means is you have all 100% of the information, and if you wish to work with the photograph, for instance in PhotoShop, which offers enhancements that can be destructive, having all the information means the damage is better mitigated, and this is the advantage of RAW.  A 16 bit RAW file offers thousands more tonal levels over an 8 bit jpg file.

Nevertheless, for most cases and general photography the jpg format set to its highest (fine) standard will provide a very satisfactory result, and with this comforting conclusion I’ll ask for permission to come ashore.