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Posting pictures on a forum
or attaching photos to your eMail

with specific notes for a forum based on vBulletin software
such as www.familywoodworking.org


There are three distinct parts to posting pictures...

  1. Reducing the pictures to a reasonable size for display on a computer screen (as opposed to the very high resolution from your camera, required for publishing or printing large copies)
  2. Uploading the pictures to vBulletin (the forum) to incorporate in your message. The recommended manner gives small thumbnail pictures which the reader can click to display larger images
  3. Alternately, there is a way to trick vBulletin into showing your pictures "full size" within your forum posts or messages

If you are trying to be nice to your email recipients, you only need to do the first step - reducing the size of your pictures.

Reducing the Size

Modern digital cameras capture a huge amount of detail - my latest digital camera creates a picture 4608 × 3456 pixels - a total of 16 million pixels. But a computer display can only show about 75 pixels per inch. An ideal picture on a forum or in an email is about 8-10 inches wide, so the display only uses 600-800 pixels in that 8-10 inches. A smart phone or tablet has more pixels per inch, but fewer inches, so a picture 600-800 pixels wide is good for that media also. You need to reduce the size of the picture to about 600-800 pixels wide before it is used on a forum. If you want to be nice to people receiving email from you, the picture should be reduced for email as well. And if you reduce the width, you need to reduce the height the same percentage - often to about 400-600 pixels high.

More technology

If you are interested in more technology about picture size, read on. Or just jump ahead to the next section on how to shrink a picture.

If you are taking pictures for a printed book or magazine, they will want a very high level of detail - typically at least 1,200 pixels per inch. A full page picture in a book may be 6x8 inches, or 7200 x 9600 pixels, or a total of 69 megapixels. Okay, you only have an 8 or 16 megapixel camera, so you need to buy a fancier camera if you want to be a professional photographer. With your hobby digital camera, the editor may only be happy to publish a small picture - maybe 2x3 inches.

If your goal is a computer screen (a picture on a forum or attached to an email), as noted above, a picture about 600 pixels wide is a good size. If you send a picture 4608 pixels wide (like the camera example above) it will take a lot longer to get to the user, take more space on his computer, and either

  1. The entire picture will be displayed. Only 20% of so of the width of the picture can be shown on the screen at a time, so the user needs to scroll to see the width. Same problem requiring scrolling for the height. Not nice for the user who can only see about 4% of the picture at a time (20% horizontally, 20% vertically), or
  2. The receiving computer will analyze the picture and reduce the size to the number of pixels that can be displayed in the window, discarding 96% of the details of the picture it just spend a long time receiving.
  3. Sometimes when you are sending email, your mail program will show you a convenient small picture, but will then go on to send the giant original picture. Why? The recipient may want to publish a book, or create a poster, and might need the detail. It will take a long time and require a lot of space, even if the only use will be to view the picture in the email. I do not know of any mail program that automatically sends the small version of a picture, even if it shows you a small picture when you are drafting the letter.

The large pictures require much more storage on the forum or on the mail recipient's computer. Time to transmit the picture will be much longer. (Remember some folks live out in the country, where high speed internet either doesn't exist or is very expensive, so slow dial up phone lines still often exist for many computer connections.) Your email recipients will thank you for shrinking the picture before emailing them.

A picture 400 pixels high and 600 pixels wide has a total of 240,000 pixels. Each pixel can be one of 16 million colors, so representing each pixel requires 24 bits, or 3 bytes. That 400x600 pixel picture requires 960,000 bytes as it is created and used. JPEG compression uses fancy mathematics (discrete cosine transforms) so a typical picture can be compressed to about 1/30 the original size with no perceptible loss of detail. That 960,000 byte picture suddenly only takes only around 32,000 bytes to store and transmit (depending on the amount of detail in the picture). Many forums have a size limit of about 100,000 bytes for a JPEG compressed picture. Even if you have a lot of detail (requires more storage in the compressed image) you will almost certainly be under the size limit.

How do you shrink a picture?

The concept of shrinking a picture is simple... If you want a picture 1/3 the original size, find the "average" color of each 3x3 block of pixels, and replace those 9 pixels with one pixel with that average color. In practice, you probably don't want to shrink the picture exactly 1/3 or 1/4 or 1/5 etc., so the technology involved is more complex, but there are lots of programs that do a good job.

PicResize web site

Go to the PicResize web site. On the first page, you have the option of dragging your (large original) picture to the web page, or search for it on your computer, or search for it on the web (if you keep your photo library on some other web site). Once you have selected your picture, continue to the next web page.

The second page on the web site allows you to

On the next screen click the icon that says "Save to Disk" - the new smaller image will be downloaded to your computer with the same name preceded by rsz (for resized). If you click the big download arrow at the top, it will install a fancy program to download your pictures, but you don't need that - the little download button at the lower left works fine, and saves the picture however you have set up your browser to download things... perhaps on your desktop or a special directory for downloads. The picture is now ready to upload to a forum or use in an email.

PIXresizer program on your computer

If you would like to install a program on your computer, rather than sending your pictures off to a web site to be resized, consider PIXresizer.

Go to the website http://bluefive.pair.com/pixresizer.htm. Download and install the program as you would any other program on your computer.

After it is installed, open the PIXresizer program. Either double-click the PIXresizer icon that was installed on your desktop or click: Start | All Programs | PIXresizer | PIXresizer to start the program. You’ll see a screen that lists the four steps:

  1. Select the picture from your computer by clicking "Load Picture." You might want to click the upper right"View" icon in the PixResizer "Open" window and select "Thumbnails" to help you select the picture you want to resize. When you have clicked on the picture to select it, click "Open."
  2. Select the target size - the larger value should be about 600 or so. If you choose a custom size, check "Maintain Aspect Ratio" so your picture isn't stretched one way or the other.
  3. Select the output file format - JPEG
  4. Click "Save the picture." Leave the box "unchecked" unless you want the picture converted to black and white. You will see a dialog that allows you to save the picture wherever you want - perhaps on your desktop or in a special folder you set up for your smaller image files. The default file name is the same but with the resolution appended - you might want to choose a more descriptive name for your purposes. Then click Save. The picture is now ready to upload to a forum or use in an eMail.

Upload the pictures to a forum

The standard vBulletin approach is that you can upload your pictures to the forum, and they will be stored and supported just as your forum messages are kept "forever." The good news is that everything is together on the forum - if you change the way you keep your pictures, or lose your computer, your wisdom on the forum remains together, unchanged. The bad news is that they are displayed as small thumbnails (nice for the user with a slow connection), and the user has to click on the thumbnail to download and view the full size pictures.

Once your nicely sized pictures are available, go to the forum. Position your cursor where you would like the picture (thumbnail) to appear in your text - it can be anywhere, it does not have to be at the end of your post. Click on the little picture frame icon near the right end of the options (if you leave your mouse over the icon for a second, it will say "insert image".

A window will open to allow you to select the files (images) you want to include in your forum message. They can be from your computer, or from your web site, or on-line photo library (from a URL). From your computer you can browse to select the files you want to upload. Since you just prepared the smaller version, perhaps with a new name, it should be easy to find and select - highlight the name(s) of the picture(s) you want to show on the forum and select SAVE. The name and location on your computer will be added to the list. When you are satisfied with the list of pictures, click the "Upload File(s)" button. The picture(s) will be uploaded and incorporated into your post at the point that the cursor was placed. Each picture will appear as the code "[ATTACH]" with the number of the picture in the forum storage, followed by [/ATTACH]. You can cut and paste to move that code, if you would like the picture in a different place in your message.

Full Size Pictures on a vBulletin forum

A full size picture is not one that comes from your camera, but one that has been properly sized to fit in the context of your forum message. The "full size" idea is that it will be displayed directly, not as a thumbnail.

The good news is that you can do it. The bad news is that you have to provide the long-term storage of the picture. If you have a web site, it can be on that web site (but once the picture is on the forum, don't move it on your web site). You might want to set up a special directory on your web site for pictures you have posted on the forum. If you have an on-line library of your pictures, and can store the nicely reduced size pictures in that library, and have a unique URL - address - that leads to each publicly available picture, you can use that photo library. (You cannot expect the forum to magically find the picture in your photo library, or log in to get access to the picture.)

A good test is to type the address of the picture (starting with http:// ) in your browser, and confirm that the one picture you are referring to appears. Note that the upper/lower case must be exactly as the picture was stored. If you have a space in the filename of the picture, it will likely be replaced by the code #20

To insert that nicely sized picture in your message,

If you want to see a preview of your post with the image in place, click "Go Advanced" at the bottom and select "Preview Post"



Special Thanks to Vaughn McMillan, of Los Angeles and Albuquerque, a talented technical writer, musician, and woodworker, who taught me the forum tricks, and has a version of these instructions on his web site.

I welcome your suggestions and corrections for this page or site.

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