Satellite Communications Blog - Beyond Expectations | Pulsar

How to Send Photos Over Your Satellite Phone

Written by Kinley Paisley | Sep 10, 2015 12:49:00 PM
Ever wonder how to send photos over your satellite phone without breaking the bank? Satellite phone speeds typically vary between 2.4kbps (Iridium and Inmarsat) to 9.6 kbps (Globalstar). That means that your Iridium or Inmarsat satellite phone has a max download speed 25 times slower than dial-up. (Globalstar is four times faster than that...so about 6 times slower than dial-up).

If you snapped a photo on your iPhone and tried to send it over your satellite phone it would take about 3 hours to send.

At that speed it's simply unfeasible to send photos over your satellite phone without compression and optimization. Beyond not wanting to wait for 3+ hours to send an image, you definitely do not want to pay for it. (Let's calculate a standard satellite airtime rate of around $1.40 per minute. You'd be looking at at least $250 to send a single image).

XGate satellite data service provides both compression and optimization, and can take a 3 hour upload timeframe down to less than a minute. Let's look how that works (and looks, in terms of image quality).

Resampling, Compression, and Image Size

There are a main things that happen to your images when they're sent via XGate:
  • Image size is decreased
  • Image is resampled
  • Image is compressed
Let's think about that picture you took on your iPhone. Because your smartphone (or any modern camera) takes high quality photos, they're going to be extremely big. A standard photo on an iPhone 6, for example, is 2448 x 3264 pixels big.

Image Reduction

The first thing XGate does is decrease that extremely large size down to something much smaller. By default it makes images 300 pixels wide.

At this point, without applying any compression or resampling, the image has a significantly smaller file size because XGate has shrunken it down by 88%.

Image Resampling

Next, XGate will resample the image. According to Google, "The term resampling is used to describe the process of reducing or the number of pixels in an image. Resampling can change the image file size as well as the image resolution."

Using a complex algorithm, XGate looks at each pixel in your image and sees how it can combine it with its neighboring pixels without completely degrading the image quality. You can set the resample rate in XGate by adjusting the quality. 100% quality means no resampling. 0% quality means complete resampling. (See below for how this affects image quality).

Image Compression

Lastly, XGate compresses the image for transmission over satellite using its proprietary compression technology. This does not affect the quality of the image.

What Images Look Like When Sent Over Satellite Phones

So let's get to the good stuff: what will your images actually look like with all this compression and resampling going on?! Turns out that we notice resampling a lot more on faces than places. We've put together two examples using the exact same resample rates and sizes so you can see the difference.

Outdoor Flowers and Stairs

This picture was taken outside the GMN offices. The detail of this picture means that you can't see the image degradation too much. All of these were sent at 300 pixels wide. (Note that depending on the screen size you're viewing this post on the images may be smaller than their original size).

Quality: 100%
Image Size: 206kb
Iridium and Inmarsat Satphone: 14 minutes
Globalstar Satphone: 4 minutes

Quality: 80%
Image Size: 63.5kb
Iridium and Inmarsat Satphone: 5 minutes
Globalstar Satphone: 1 and a half minutes

Quality: 50%
Image Size: 33kb
Iridium and Inmarsat Satphone: 2 minutes
Globalstar Satphone: Less than 1 minute

Quality: 30%
Image Size: 17kb
Iridium and Inmarsat Satphone: Just over 1 minute
Globalstar Satphone: Less than half a minute

Quality: 15%
Image Size: 12.8kb
Iridium and Inmarsat Satphone: 1 minute
Globalstar Satphone: Less than half a minute

Quality: 0%
Image Size: 12.1kb
Iridium and Inmarsat Satphone: Less than 1 minute
Globalstar Satphone: Less than half a minute

Faces

Humans tend to notice details on faces much more than on, say, plants, which is why you'll probably notice the resampling on these photos more than with the ones above. Special thanks to our intrepid sales and marketing manager Kinley for providing the selfie! All of these were sent at 300 pixels wide. (Note that depending on the screen size you're viewing this post on the images may be smaller than their original size).

Quality: 100%
Image Size: 130kb
Iridium and Inmarsat Satphone: 9 minutes
Globalstar Satphone: 2 and a half minutes

Quality: 80%
Image Size: 36.4kb
Iridium and Inmarsat Satphone: 3 minutes
Globalstar Satphone: Under 1 minute

Quality: 50%
Image Size: 18.2kb
Iridium and Inmarsat Satphone: Just over 1 minute
Globalstar Satphone: Less than half a minute

Quality: 30%
Image Size: 9.6kb
Iridium and Inmarsat Satphone: Less than one minute
Globalstar Satphone: Less than half a minute

Quality: 15%
Image Size: 7.3kb
Iridium and Inmarsat Satphone: Around half a minute
Globalstar Satphone: Less than 20 seconds

Quality: 0%
Image Size: 6.9kb
Iridium and Inmarsat Satphone: Around half a minute
Globalstar Satphone: Less than 15 seconds

What's the Takeaway?

All news is good news when it comes to sending images over XGate. Whether you're sending them via email or posting them to Facebook or Twitter (all possible directly within XGate), image quality remains great even with significant resampling and the time to send them is incredibly small, especially when you consider what it would take to send without using XGate!

You can learn more about all the features of XGate, including an important one for sending images (Mid-File Restart), on the XGate page.

Try the XGate Free Trial

Interested to see if XGate is a good fit? You can try a free 3-day trial of XGate here.
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