Prepping Photos for the Forum
Detailed steps in the basics of editing photo images ("post-processing") will be posted in another a tutorial, but this tutorial will also cover the last few steps necessary to reduce the size
of an image. Like all forums that allow images, this forum has limits on file size and type. It is important to make sure that your photos meet these limits.Workflow Summary
Like any process, a key issue is efficiency. A suggested workflow:
1) Open image and check/adjust exposure.
5) Change image to 8 Bits/channel mode (I shoot raw)
6) Reduce color density (Save for Web in PhotoShop Elements)File Type
For photo images, "JPEG", "GIF", and "PNG" files are the photo file formats supported by this forum. Respectively their 3-digit file extensions are ".jpg", ".gif", and ".png". For example, if a file is named "MyPic.jpg", the ".jpg" indicates that the file is formated in JPEG format. JPEG-formatted files are by far the most common format generated by digicams.
The "GIF" format is very good format for limited-color drawings and simple images. It's advantage is that it's file size is typically smaller. "PNG" is also a useful format for some images. Some cameras produce "RAW" formatted files. If using any of these formats, convert them to "JPEG" format for this tutorial.
Note that you can upload .pdf (PDF documents) and mpg (videos) files but those are another topic that's out of scope for this tutorial.File Size
Like most forums, this forum limits the number and size of uploaded files. If your file is larger than that it won't upload. Check these before uploading. For purposes of this tutorial, we'll assume that the size limit is 150KB. You MUST reduce your image size to this limit.
So what affects file size? Three things - number of pixels in the file, number of colors (bits per pixel), and quality. You can use Photoshop, IrfanView (and other editors) to change these. (See below for instructions.)
- Number of Pixels - You've probably seen terms like "5 Megapixels" and "800 X 600". The first is typically used in the camera world; the second typically refers to monitor resolution. Even earlier model digicams produced 2 megapixels (two MILLION pixels). This is the size of the image your camera produces. Large number of pixels = large file size.
- Number of Colors - Cameras produce images with millions of colors. Large number of colors = large file size.
- Quality - Cameras produce very high quality images. High quality = large file size.
My wife's 5 megapixel Sony digicam creates two megabyte files - WAY larger than you can upload. These files are saved at full size and full resolution (5 megapixel), with the maximum number of colors, at the highest quality level. That's the start.
But that size, quality, and color density is NOT necessary for publishing to the web. 99.9% of the time, you don't want this for your images. A 2500 X 2000 pixel image is too large for the screen, the files size is too large to upload, and most people could never tell the difference in image quality. So, manipulating the file's number of pixels, number of colors, and quality to acceptable limits are the keys to reducing your file size for publishing.Key Steps to Reducing File Size
1) Crop out the extraneous - Cropping is like using scissors to trim a paper picture. It reduces image and file size.
2) Reduce the image size - Most editors have the ability to reduce the size of the image. The simply eliminates some pixels. This makes the image look smaller on your screen and reduces the size of the file. A good size for publishing is probably about 500 to 800 pixels height and/or width. Much larger than about 900 pixels may make it a bit difficult for some people to display on theirs screens. Much smaller than about 400 pixels doesn't show enough details. I aim for about 440X400 for inline pics and about 800X600 for attached pics.
Here's a pic of my drill at 444 (height) by 430 pixels:
That's not too bad, but here's the same pic at 800X600:
Which one is better? Well it depends... The bigger pic shows much more detail. But it also shows the warts. The screw bit in the chuck looks decently sharp at 400 pixels, but shows that it is out of focus at 800 pixels.
3) Save for web/reduce quality - Different editors use different terms, but most will allow you to reduce the quality level and number of colors for web publishing. In PhotoShop Elements for example, you "Save for Web". You can change the "Quality" slider and see the file size go down. When you zoom in, you'll see the colors get a bit blocky and the image gets grainy, but it's still OK for publishing.
4) When the file is at the correct size and you're happy with the looks. Save the file to a NEW FILE NAME. By habit, I choose a name something like "<original file name>_Reduced". E.g. if original file is "MyPic.jpg", the reduced file would be "MyPic_Reduced.jpg".