Overview of Various Image File Formats

Posted on Sep 17, 2007 in Digital Cameras, Digital Photos | 7 Comments

There are many different image file formats in use on Web pages today. Each file format has its advantages and disadvantages, and can be used for specific images. For those that use digital cameras you may be familiar with one format, while you may have heard of others.

In this post I will provide an overview of the different formats including their advantages and disadvantages.


GIF Format

I will begin with one of the oldest formats in use on the Internet today. The GIF name is a acronym for Graphics Interchange Format, and was first introduced by Compuserve in 1987. This is a popular format next to the JPEG format and is still used on Web pages today. Digital cameras, however, don’t use this format because it only supports 256 colours.

There are currently two versions of GIF in use: GIF87a (the original version) and GIF89a. The GIF89a version supports multiple images in stream which allows you to create animated GIF images.

Advantages – One advantage to a GIF is that it uses lossless compression to make an image smaller. This means that no image information is lost during compression. It also has the advantage of making one of the colours in the image transparent to allow the background to show through. As mentioned earlier, you can create simple animations by combining multiple images into a single GIF89a file.

Disadvantages – The biggest disadvantage for the GIF file format is that it only supports 256 colours, which isn’t nearly enough for a digital photo. This means that GIF files are restricted to sharp-edged line art (such as logos) that have a limited number of colours.

JPEG Format

This is perhaps the most popular file format used for digital pictures, especially now that all digital cameras store their pictures in this format. Similar to GIF, JPEG is also an acronym for Joint Photographic Experts Group. This group was first formed in 1986, issued a standard in 1992, which was approved in 1994.

Unlike the GIF file format, the JPEG format can compress images that contain up to 16.7 million colours. This is more than enough for a digital photo. Besides the number of colours, another difference between the GIF format and the JPEG format is the type of compression used. While a GIF uses a lossless compress, a JPEG file is compressed using a lossy compression algorithm. This means that each time you save a JPEG file, it loses more information.

Digital cameras may also have the ability to save a picture in the RAW format. This format, however, is a proprietary format that is different between cameras manufacturers, so it isn’t used at all on the Internet. For more information about the JPEG and RAW file formats, please read JPEG or RAW Format.

Advantages – The biggest advantage is the ability to save a digital photo in a very small size (in bytes). Another advantage is that it can save an image that includes up to 16.7 million colours, which is more than enough for a digital picture. It is a very popular format for those two reasons alone.

Disadvantages – The biggest disadvantage is that the compression used in a JPEG image is lossy. Each time you save a JPEG image, the more data you lose. Another disadvantage is that if you compress an image too much, you will get JPEG "artifacts". These look like distorted sections of the images, usually looking like squares. You should minimize the amount of compression of the image, while at the same time managing the size of the file, to reduce these artifacts.

TIFF Format

As with many names in the computer world, the TIFF name is also an acronym. TIFF is short for Tagged Image File Format. This a very popular format for archiving digital photos, mainly because it is widely supported by most image editing programs across many different operating systems.

Similar to the JPEG format, it supports 24-bit (16.7 million) colours. You can even save up to 48-bits of colour information within the file. The trade off is the file size. While JPEG files are compressed, TIFF files are generally uncompressed, which results in very large file sizes. You can, however, compress TIFF files but not to the same size of JPEGs.

Advantages – Since the TIFF file format is supported by pretty much all image editors on many different operating systems, it is the first choice for archiving digital photos. Since TIFFs don’t use compression, at least by default, you can continuously save a TIFF file and never lose any information. When editing photos, it is best to first save the file in a TIFF format during editing, and then JPEG once your are finished.

Disadvantages – The biggest disadvantage for a TIFF file is the size. Compared to JPEGs, TIFF files are enormous. Depending on the bit depth (24 or 48) you are talking 100MB+ for a single file. Although, with the size of hard drives and DVDs it will be worth it to save your photo archives in the TIFF format.

PNG Format

Rounding out the acronym file names is the PNG format, or Portable Network Graphics. This format is similar to the GIF format in that it uses a lossless compression. Years ago there was a patent issue with the compression used for the GIF format, so the PNG format was created to avoid any patent issues. This format is fairly new compared to the other formats since it was introduced in 1996.

One advantage the PNG format has over a GIF is the number of colours it supports. The PNG format supports 24-bit or 16.7 million colours. This means that it can be used as a format for your digital photos. The JPEG format, however, still compresses the file to a much smaller size, and has more support by image applications.

Advantages – One advantage that the PNG has over a GIF is the number of colours. It can support 16.7 million colours, which is the same as a JPEG file. It also uses a lossless compression, which means that you can save your image many times without losing any information.

Disadvantages – Since this format is new compared to the others discussed in this post, it doesn’t have the same amount of support. The older Web browsers will have trouble displaying a PNG image, but the newer browsers should have no problem. Although it can compress a 16.7 million colour photo-quality image, the JPEG file format can still create a smaller file size. If you do want to print your photos from a PNG format, ensure your photo lab supports the PNG format.

Summary

In this post I discussed the most popular image file formats in use today. Each format has its advantages and disadvantages and is suited for specific types of images. Some images are also suited for specific tasks, such as printing and archiving. The formats discussed here can be edited by most image editing software without any problems.

Network Glossary of Terms

Posted on Sep 14, 2007 in Networking | 3 Comments

I have written several posts regarding networking your home computers to the Internet. With more and more people using broadband as their Internet connection, it is becoming more common to see home LANs to allow multiple computers to connect to one Internet connection. To setup a network, it is also important to understand some of the terminology used so you have a better understanding of what is involved in establishing a home LAN.

In this post I will provide a glossary of networking terms (alphabetically) that you will see when creating a home network. This will be helpful when you configure your router but are unsure of a specific networking term.


Networking Terminology

AES – An acronym for Advanced Encryption Standard. A symmetric encryption algorithm used to protect data. This is aimed at replacing DES. It is one of the encryption options for a wireless network when WPA or WPA2 is used.

DHCP – An acronym for Dynamic Host Configuration Protocol. This is a communications protocol that allows network administrators manage and automate the assignment of IP addresses through a network. Every time a device connects to the network with DHCP it can be assigned a different address.

DNS – An acronym for Domain Name System. This is a system that translates the Internet domain names into their respective IP addresses. This information is usually stored in a database and a service will then lookup the IP address for a specific domain name. When an address is type in a Web browser, a DNS lookup is performed to find the actual IP address.

Gateway – A network point that acts as the entrance to another network. The router acts as the gateway to your local network, when you access the Internet through the router.

IP Address – Short name for Internet Protocol Address. This is a series of four numbers separated by dots, for example 192.168.1.1. Every computer connected to a network has its own unique IP address.

LAN – An acronym for Local Area Network. This is a network that covers a small, local area such as a home or office. A LAN network can be configured to transfer data at a high rate of speed.

SSID – An acronym for Service Set Identifier. A unique keyword of up to 32 characters (letters or numbers) that a wireless network card can connect to. For home users, this identifier can be set within a wireless router. This SSID of a wireless network can be broadcast to all computers within range of the signal to allow the computers to connect to the network.

TKIP – An acronym for Temporal Key Integrity Protocol. A security protocol designed to replace WEP on wireless networks without replacing legacy hardware. If can select TKIP when you specify WPA within your wireless router.

WAN – An acronym for Wide Area Network. Unlike a LAN, a WAN covers a much larger geographical area, and is usually comprised of one or more LANs.

WEP – An acronym for Wired Equivalency Protocol. A security protocol that provides a minimal level of security for a wireless network. It has flaws that skilled hackers can exploit. Use WPA if both your router and computers of capable of using it.

WPA – An acronym for Wi-Fi Protected Access. This is a replacement data encryption method that replaces the much weak WEP protocol. It is an improvement over WEP because it uses dynamic keys when encrypting the data. This is done by utilizing TKIP to encrypt the data.

Vista Power Saving Settings – Increase Laptop Battery Life

Posted on Sep 12, 2007 in Windows | 1 Comment

In a previous articles titled Conserving Your Laptop Battery Power I listed several tips you can use to help conserve your laptop battery. The tips in that post can be applied not only Vista, but also previous versions of the Windows operating system.

In this post, however, I will discuss a new utility within Vista to help you get even more time out of your laptop battery.


Vista Power Options

Similar to the previous versions of Windows, you can access the power options for Vista from the control panel. To access the options use the following:

Click Start Menu->Control Panel->Mobile PC->Power Options.

Within the dialog you will see several default power options. You can simply click one of the options to use the power settings associated with it. Each power option has different battery life and performance features.

When you increase the battery life you usually take a performance hit. When you increase the performance of your laptop, you will usually reduce the battery life of your laptop. You need to determine how much of a performance hit you can take while on your battery and still do what you need to accomplish.

If you want more control over the battery life and performance ratio, you can use the advanced settings and control many of the different power options for different hardware on your laptop.

Advanced Power Settings

In addition to the specified power options, you can customize the power settings of those options. This allows you much more control over such things as how much power your CPU will consume and the brightness of your LCD display.

To use the advanced settings, use the following steps:

  1. Click Start Menu->Control Panel->Mobile PC->Power Options

    2. The power options dialog should now appear on the screen with the saved power options listed.

  2. Select a power option you would like to change and click Change plan settings hyperlink.

    3. The options associated with the power settings will now be shown on the screen. Although you can change these options, we will go even further to get much more control over how the battery power is used.

  3. Click Change advanced power settings hyperlink.

    4. The Power Options dialog is now displayed on the screen. Click the plus sign next to each option to show the power options for each.

Each of the options has an On battery and Plugged in setting. The On battery setting specifies what Vista should do when your laptop is running on the battery. Once you plug in your laptop, the settings specified in the Plugged in setting will take effect.

One of the options I found useful within the advanced settings was the Processor power management. This allows you specify how much power is used to run your processor. Obviously, the lower the power, the less performance you will get, but when you are on battery, you shouldn’t be running any processor intensive tasks.

Summary

When Vista was going through testing, many people complained that their laptop battery wasn’t lasting as long as under a previous version of Windows. Vista allows a laptop user the ability to really customize their battery consumption by deciding how the battery power should be used. By reducing the performance of some of the hardware of your laptop, you can significantly increase the life of your battery. As always, however, the total length of battery time is also dependent on the type of processor and battery in your laptop.

Securing the Linksys WRT54G Wireless-G Router

Posted on Sep 10, 2007 in Networking, Security | 70 Comments

I discussed securing your wireless network in a post titled Securing a Wireless Network. I currently have a Linksys WRT54G Wireless-G router. When I work from home I use this router to connect to work through VPN, and have done it with out any problems.

The big issue with wireless networks is security. As anyone with a wireless network card within a few hundred feet of your router can connect to your router. To prevent this from happening, it is important to secure your router.

Click to continue reading »

Stop Programs from Running When Windows Starts

Posted on Sep 7, 2007 in Windows | 3 Comments

One of the many complaints users have of Windows is the slow start times they may experience. Some of the time, the slow start time is due to the number of programs that are loaded when Windows starts up. These programs will sometimes create an icon in the system tray near the time in the lower right part of the screen. Others may load but give no indication that they are loaded, except when viewing the processes.

There may also be times when one of the applications causes your system to crash. The reality is that most of those programs don’t need to start up, but are there to make your life easier. In this post I’ll explain several ways of preventing those programs from loading when Windows starts.


Microsoft System Configuration Utility (MSConfig)

This is one of the handy utilities included with the Windows operating systems. It was first included with Windows 98, and it is also included with Windows ME, and Windows XP. For those on Windows 2000, you can copy the msconfig.exe version from Windows XP.

The purpose of the system configuration utility is to help troubleshoot system problems by allowing you to modify your system configuration. This is done by checking and unchecking a series of checkboxes. I mainly use this tool to help control the programs that are loaded at startup, since it will list all programs in an easy to read list.

To manage the programs that startup when Windows starts, use the following steps:

  1. Click Start->Run to open the Run dialog box.
  2. In the dialog type msconfig.exe.

    3. The tool displays several tabs at the top. The one will be focusing on here is the Startup tab.

  3. Click the Startup tab.

    4. A list of all the programs that start when Windows starts is listed, along with where the program is called from. We will discuss the various locations later in this post.

  4. Read through the list and uncheck any programs that you don’t think you want loaded. Don’t worry, the program won’t be deleted from your computer, it is just being prevent from starting when Windows starts.
  5. Once you are satisfied with what is left in the list, click the OK button, and then accept the reboot prompt to allow your computer to restart.
  6. Once your computer restarts, you will notice that the programs you specified not start no longer start.

Windows Startup Locations

The startup programs list contained a column called Location. What is the value that is displayed there, and how does it affect the loading of the programs?

There are many locations within Windows that you can copy or create a shortcut to an application that will cause it to load once Windows starts. There are two in the registry and two in the start menu.

Startup in the Start Menu

I will start with the start menu, since you may be more familiar with that one. When you display your start menu, you may notice a folder in there called Startup. This is system folder that displays programs that will start when Windows loads. Although only one is displayed, there are actually two startup folders that are used.

When you right-click the Start Menu button, and select Explore, you will open Windows Explorer to the Start Menu directory for your login ID. If you expand the Programs subfolder, you will see the Startup directory associated with your login ID. If you scroll through the list of login IDs, you may see one called All Users. Expand that folder, and you will see the Start Menu and Programs folders that applies to all users of you system. There is also a Startup folder in there as well.

Simply delete a shortcut from the Startup folder to prevent the program from loading once Windows starts.

When Windows loads it first executes any programs in the All Users startup, and then the Current User startup. Before those programs are executed, however, Windows first runs programs specified in the registry.

Startup in the Registry

I recently wrote a post titled Understanding the Windows Registry where I explained the various registry hives. The two hives we will be looking at here is the HKEY_CURRENT_USER and HKEY_LOCAL_MACHINE.

Within these two hives are contain the key structure: SOFTWARE\Microsoft\Windows\CurrentVersion\Run. If you navigate down through this structure in each of the two hives you will notice a list appear on the right side of the editor.

This list contains the programs that start once Windows loads. The Name column is the name of the program while the Data column contains the complete path to the executable. You can edit any of the entries by simply double-clicking the entry.

Simply left-click a program in the list and press the Delete key to prevent it from loading once Windows starts.

Summary

It is really easy to prevent a program from loading once Windows starts by using the Microsoft System Configuration utility. Simply uncheck the checkbox associated with the program to stop it from running.

The more advanced users may want to delete the program’s shortcut from the startup folder in the Start Menu, or the string value in one of the Run keys in the registry. For most users, however, the MSCONFIG utility will do the task nicely.

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