Tuesday, March 6, 2012

Techno TidBit About PNGs

As part of Cheri's Dream Big Designs CT, I get to write up some hints and tips.  Here's one I wrote last Sunday about PNGs. 

I've been using Photoshop Elements for a while now, but I still amazed at how many buttons and tools I rarely use and how many technology terms I'm not familiar with.  So let's see if we can't learn a few things together.  Today I'll be talking about PNGs and saving options.

Developed in 1995, PNG stands for Portable Network Graphics, typically called "ping", and is an image file format that was designed to replace the GIF format.   The PNG file format offers better compression (meaning smaller file sizes) and more color support than GIFs.  GIFs only support a color palette of 256 colors while PNGs support millions of colors.  GIFs are widely used today for animated files (like blinkies) because PNG doesn't support animation.   File formats are important for web display and for image editing.  From our digital scrapbooking perspective, all embellishments are saved as PNG files.

OK, so if embellishments are PNG files, why are papers, layouts and photographs stored as JPG files?  It's because of transparency.  When you crop your PNG, it's still in a rectangular size, but you only see the embellishment itself and the rest of the cropped outer space is invisible or transparent.  If you crop your embellishment and try to save it as a JPG, it would add a solid white background behind the element to fill the entire cropped space.  Make sense?

When you're creating an embellishment and getting ready to save it, you get this option box.  Do you know which option to select?


Choosing the interlaced option means that several "versions" are saved of the image inside the file (like going from a fuzzy image to a crystal clear image).  That's what makes the file size larger.  A while back when we were using really slow modems, this was a good thing because at least some image would appear on your screen and then get progressively clearer.  With the old modem and a non-interlaced PNG, you'd see nothing on the screen until the entire image loaded.

With today's faster cable access to the Internet combined with computers having faster processors and more memory, there's no substantial benefit of interlaced files because the response time is so quick.  So choose "None" for your PNG Options.  But let's try an experiment just for fun.

Here's a word art cluster I made with Dream Big Designs' 'Lucky Day' kit.  This version I saved as a PNG with the "None" option.  File size is 4.3mb.



Here is the version I saved with the "Interlaced" option.  File size is 4.9mb, that's almost 14% larger.


Did you see any difference in how quickly it loaded?  What if you hit refresh and check it again, or scroll up and down this blog post?  Your computer probably loaded it so fast that you couldn't see any difference at all.  Now you know it's OK to click "None" when you're saving a PNG and feel comfortable that you made the right selection.    Hopefully you learned a little techno tidbit today.  Have a great week! 

1 comment:

  1. linda, can I just say that I NEVER know which to pick on the PNG question of none or interlaced!? You rock! thank you!

    ReplyDelete