Sharing Your Orchid Pictures

Another aspect of the wonderful world or orchids is photography, and the expansion of digital imagery has really been a boon. Over time, one can amass quite a collection, and you’re bound to want to display them – individually or as a group.  Sharing your orchid pictures is a great part of the hobby.

Where to Post Images

You have several choices here. Many internet service providers allow you to create your own personal web pages at no charge, so you can pretty much do what you want. Alternately, there are free services out there such as webshots.com or pay services such as pbase.com, where you can maintain a portfolio of images. If your willing to post images individually, there is my favorite, the “Orchid Art and Pictures” forum at The OrchidSource as a web-based alternative, and the orchidphotos@googlegroups.com mailing list.

Resize Before You Post!

Many digital cameras offer a variety of size and resolution settings for the stored images. Shooting and storing them at the largest size and maximum resolution is preferred because that combination gives you the best overall image. That image file, however, is NOT appropriate for posting online. Below is a short guide, not “How to,” but “Why” one should resize images:

  • Premise 1: You are posting the image to get help, compare flowers, share a treat, or just show off a bit.
  • Premise 2: Accordingly, you would like to make the image easy and convenient for the viewer to see. The logic being that if your image is too big to see on the viewer’s monitor, or the file is too big and slow to download, the viewer will just “pass” and the qualifications of “Premise 1” won’t be met.

One has to think in terms of a combination and interaction of file size, dimensions of the image, resolution, and color depth.

File size is important as it affects the download (and upload) speed for the file. What makes up the those bits of data are the other three components mentioned above.

If you consider 640 x 480 a minimum standard screen size (lowest common denominator for most computers) and take into account the browser components and headers and margins created by the various types of viewing software, it appears that a file of about 400- 450 pixels tall by about 500-600 pixels wide is a decent range to work in.

The resolution – pixels per inch – works with the parameter above to 1) set the viewable size of the image, and 2) determine the file size.

Color depth – bits per pixel – is a significant factor in the final file size as well. In any image, one or more bits of data may be attached to each pixel to define its appearance. At 8 bits it can have 28 = 256 different colors or shades of gray. Add a second byte, and you can further control the intensity of each of the 256 colors to yield 216 or about 65,000 different colors. Add a third byte and the number comes in at about 16-million colors, approximating the sensitivity of the human eye.

So how does that affect the file size? Let’s take for example a 600 x 450 pixel image. If it is black and white, each pixel only needs a single bit to describe the color – on/off or white/black – so our image is 270,000 bits or 33.8 kilobytes (kb) in size (8 bits = 1 byte). Adding additional bits to each pixel adds to the variety of “colors” available, but multiplies the file size. That same image at 65k colors (16 bits) results in a file that is 540 kb in size, and going all the way to the “true color” of 24 bits gives us a file that is 810 kb. (Those numbers do not exactly match the file size, as different file formats can include compression, it can vary based upon the number of colors you use from a “pallet,” and when transferring or storing them, there are additional pieces of data attached to the file.)

Now for an image-size example… If you have a 600 x 450 image, saved at 150 ppi, the “native” size will be 4″ x 3″ (600÷150=4, 450÷150=3). If it is saved at 75 ppi, it becomes 8″ x 6″.

Now let’s look at the monitor. Consider a 17″ (diagonal – actually just over 14″ wide) monitor with the resolution set to 1024 x 768 pixels. That means that my resolution is 72 ppi. If my resolution was 640 x 480, that would be 45 ppi, so the 4″ x 3″, 600 x 450 image saved at 150 ppi would be displayed as 13.33″ x 10″!

Wrapping all this up… I have found that an image about 500 pixels wide by 400 pixels tall saved at 16 bits per pixel and 72 ppi seems to be fine for sharing, although I keep “deeper” versions for printing purposes. With those parameters, on my monitor the 500W x 400T image is about one-half of the width and height of the screen, while on the 640 x 480 monitor set at 72ppi it occupies about 80% of the screen, but is still viewable without scrolling.

Now then, if I was to post picture “as taken” with my digital camera as it is currently set up (2160 x 1440, at 24 bits/pixel, I’d be working with a 9.3 megabyte file (before jpg compression) and it would appear to be approximately 20″ wide on my monitor, or almost 32″ wide on the 640 x 480 monitor!

Using Science & Logic to Improve Horticulture