A Quick Way to manage Outlook email signatures

Jesper Frier · Last edited by Jesper Frier on Mon Nov 09, 2009 2:06 pm; edited 3 times in total

Guidelines for selecting the appropriate image format in your email signature

Email messages often contain images, graphics and other design elements. When a message is sent in the HTML format, images used in the message body can be either linked or embedded using one of below 3 formats of your choice.

JPEG: Joint Photographic Experts Group
JPEG pictures store a single raster image in 24-bit color. JPEG is a platform-independent format that supports the highest levels of compression; however, this compression is lossy. Progressive JPEG files support interlacing.

The level of JPEG file compression can be increased or decreased. However, image quality is sacrificed for file size. The compression ratio can be as high as 100:1. (The JPEG format comfortably compresses files at a 10:1 to 20:1 ratio, with little picture degradation.) JPEG compression works well with photo-realistic artwork. However, for simpler artwork with fewer colors, sharp levels of contrast, solid borders, or large solid areas of color, JPEG compression does not provide superior results. Sometimes the compression ratio is as low as 5:1, with a high loss of picture integrity. This loss occurs because the JPEG compression scheme compresses similar hues well. But the JPEG compression scheme does not work as well with sharp differences in brightness or with solid areas of color.

Advantages:
- Superior compression is supported for photographic artwork or realistic artwork.
- Variable compression allows control of the file size.
- Interlacing (for Progressive JPEG files) is supported.
- JPEG is a widely supported Internet standard.
Disadvantages:
- Lossy compression degrades the original picture data.
- When you edit and resave JPEG files, JPEG compounds the degradation of the original picture data. This degradation is cumulative.
- JPEG is not suitable for simpler pictures that contain few colors, broad areas of similar color, or stark differences in brightness.
GIF: Graphics Interchange Format
GIF pictures store single raster image data or multiple raster image data in 8-bits, or 256 colors. GIF pictures support transparency, compression, interlacing, and multiple-image pictures (animated GIFs).

GIF transparency is not alpha channel transparency and cannot support semitransparent effects. GIF compression is LZW compression, at a roughly 3:1 ratio. Animated GIFs are not supported in Outlook 2007.

Advantages:
- GIF is a widely supported Internet standard.
- Lossless compression and transparency are supported.
- Animated GIFs are prevalent and easy to create with many GIF animation programs.
Disadvantages:
- GIF supports only a 256-color palette; therefore, detailed pictures and photo-realistic images lose color information and look paletted.
- Lossless compression is inferior to the JPEG format or the PNG format, in most cases.
- GIF supports limited transparency and no semitransparent effects or faded effects, such as those that are provided by alpha channel transparency.
PNG: Portable network graphics
PNG pictures store a single raster image at any color depth. PNG is a platform-independent format.

Advantages:
- PNG supports high-level lossless compression.
- PNG supports alpha channel transparency.
- PNG supports gamma correction.
- PNG supports interlacing.
- PNG is supported by more recent Web browsers.
Disadvantages:
- Older email clients may not support PNG files (e.g. Lotus Notes 6 and 7).
- As an Internet file format, PNG provides less compression than the lossy compression of JPEG.
- As an Internet file format, PNG offers no support for multi-image files or animated files. The GIF format supports multi-image files and animated files.
- There are instances where .png files do get degraded in certain circumstances when they come back from others.

Resolution and color depth

embed your image

On-Screen Display:
We recommend a resolution of 72 pixels per inch (ppi), because most monitors still have between 60 pixels and 80 pixels per inch. Saving at a higher resolution does not result in a higher-quality display, because your monitor cannot display more pixels than physically exist in the monitor.
Printed output:
How to create good printed email is a complex subject, because of the vast number of printers that are available and the capability of each printer to produce color output. The primary factor for good printed output is the number of lines per inch (LPI) that your printer is capable of printing.

To calculate your target resolution, you can multiply the LPI of a typical Laser printer by two. This is a general rule.
This results in a resolution of 130 pixels per inch (ppi) if you want your printed emails to look nice on paper.

Glossary

Compression: Compression is a mathematical scheme that makes a picture file smaller by removing redundant information. There are two types of compression: lossless and lossy.
Compression, lossless: Lossless compression is a compression scheme that emphasizes maintaining the integrity of the original picture. When the picture is uncompressed, it maintains the same resolution and picture quality of the original, uncompressed picture.
Compression, lossy: Lossy compression is a compression scheme that emphasizes producing a small picture file, even at the cost of picture quality. Lossy compression can produce smaller picture files than lossless compression; however, when you uncompress the picture, some of the original picture data is lost and cannot be recovered.
File size: File size is the ultimate limiting factor when you work with picture files. File size is the most common cause of problems when you work with pictures in Microsoft Office. File size is determined by the following factors: picture size, resolution, file format, compression, and color depth.
Interlaced: Interlacing is a method to send picture data over the Internet. When a picture is interlaced, the following occurs: After one sixty-fourth of the picture is downloaded, you can see a general image of what the picture looks like. As more of the picture is downloaded, the resolution improves until the whole picture is displayed.
Pixel: A pixel is a fundamental unit of measurement in a raster-based picture or on a monitor. Both raster pictures and monitors are defined by rows of dots that can be individually assigned a color. These dots are called pixels.
Resolution: Resolution is the amount of picture data in a specific area of a picture. Resolution is usually defined in pixels per inch. The higher the resolution, the more precise and clear the picture is. However, when you increase the resolution, the file size of a picture also increases.
Transparency: Transparency is a method that allows areas of a picture to appear transparent, therefore revealing the background. There are several methods of transparency, including alpha channel transparency.

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</Jesper> | Email Signature Health Check | Email Signature Showcase

Jesper Frier · Posted: Tue Jan 13, 2009 6:16 am Post subject: Here's a good rule of thumb

Here's a good rule of thumb

If the graphic is a photograph, use a JPEG image type with a low to medium image quality.
If the graphic is clipart or primarily fonts with few gradients, use a GIF image type.
GIF images can display up to 256 colors, but the file size will be larger. Reduce the number of colors in the image as far as you can without noticeably degrading image quality. I try for 16 to 32 colors if possible. It makes for fast-loading graphics.

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</Jesper> | Email Signature Health Check | Email Signature Showcase

Jesper Frier

Completed a email signature design test for one of my clients, and we found out that their PNG logo was not supported in Notes 6 and 7, and we changed the logo to JPG.

PNG images are not supported in Notes 6 and 7

Both 8-bit and 24-bit PNG's are displayed as broken images in Notes 6.5.4 and Notes 7.

Yes

Thankfully, Notes 8 offers full support for PNG.
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</Jesper> | Email Signature Health Check | Email Signature Showcase