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AdobeCoussini
Currently Being Moderated

8 or 16 bits, that's the question

Apr 4, 2012 5:06 AM

Tags: #dreamweaver

I want to know wich color deep must i take for my web site.

 

Just to learn some word about me, i a new born in this websitedesign world.

 

But i know that many user have a good monitor can be use 16 bits or more in colors.

 

So, i know that you can create gradient color in your web page.

 

Finally, 8 bits is it "IN" or "OUT" actually. Is is old stud, and should i go for 16 bits for any web browser.

 

Thanks.... a lot for any answer.

 

Sorry, i speak french usualy !

 
Replies
  • Currently Being Moderated
    Apr 4, 2012 6:02 AM   in reply to AdobeCoussini

    You say you are new to web design, but are you new to design?  I ask because if you are speaking in terms of something like Photoshpo with 8 bits per channel, then yes 8 bits is more than sufficient.  More than that is only needed for print mediums.

     

    When discussing file formats, I would typically stick to PNG or JPG depending on the nature of the image and whether or not you need transparency.  For instance PNG supports transparency in images whereas JPG files do not.

     
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    Apr 4, 2012 7:24 AM   in reply to AdobeCoussini

    Hi

     

    An 8 bit color palette will only give you the old 256 web safe colors to use, and whilst this used to be very important it has fallen into disuse as modern computers, (and most smartphone/tablet devices) can support millions of colors.

     

    The question on which to use 8/16/32 bit, (or even 64 bit) should depend on what and who you are designing/building the web site for. As an example if it is for a professional photographer then 32 bit would show the work of the photographer much better, but, (and this must be remembered) download speed/time must also be taken into consideration as there is little point in using 32 bit images if the page, (with images) size then requires the user to download 15Mb+ of image data and takes 5 minutes to appear on the screen.

     

    PZ

     
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  • Currently Being Moderated
    Apr 4, 2012 7:38 AM   in reply to AdobeCoussini

    When you use SAVE FOR WEB in Photoshop or Illustrator, all images are saved as 8 bit, that's because it is impossible to use 16 bit images on the web. If anyone doesn't believe me, try using a 16 bit image. It will not work.

     

    As for image type, I try to use GIF as much as possible, for clean graphical elements. You have good control and the images can be very small.Of course it is not the type of choice for photographs.

     
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    Apr 4, 2012 8:24 AM   in reply to Rob Hecker2

    Rob Hecker2 wrote:

     

    When you use SAVE FOR WEB in Photoshop or Illustrator, all images are saved as 8 bit, that's because it is impossible to use 16 bit images on the web. If anyone doesn't believe me, try using a 16 bit image. It will not work.

     

    Hi Rob

     

    What you are talking about is the bits per color pixel which is 8 bits, but as this would create a 24 bit rgb colormap image, then the jpeg image is considered to be 24 bit, this type of colormap bit can be used on the web and will be displayed.

     

    IE9+ and Safari, (just think hd images on iPhone/Touch/Pad3) FF and Opera do support and display true color images which can be 24 bit, and devices such as those using the retina display go above this, (that is why everyone is now saying that hd images are now required for the iPad3) for info on true color images see - http://en.wikipedia.org/wiki/Truecolor#Truecolor

     

    PZ

     
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    Apr 4, 2012 10:19 AM   in reply to pziecina

    PZ, thank you for the link. That is interesting. However, what I am  calling 8 bit is TrueColor. See the following:

     

    True" color is also called 24-bit color . Here, each color is 8 bits, for a total of 24 bits. Since each color has 256 shades, we can multiply 256 for red, times 256 for green, times 256 for blue and get millions of colors, (256 x 256 x 256 = 16,777,216). Millions of colors are pretty much what's accepted for a monitor's colors to look "true" to the human eye.

     

    Images from high end cameras and scanners can be 16 bit, which cannnot be used on the web. When you are in photoshop, you will see on the bar above the image (image.jpg @300%(RGB/8#) or (image.jpg @300%(RGB/16#). The 16 bit image is not only not going to render in most browsers (or any) but it's going to be a much larger file, so even if it did render, it would probably not be wise.

     
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    Apr 4, 2012 10:30 AM   in reply to Rob Hecker2

    Hi Rob

     

    That's why I said in my reply to your original post -

    "What you are talking about is the bits per color pixel which is 8 bits, but as this would create a 24 bit rgb colormap image, then the jpeg image is considered to be 24 bit, this type of colormap bit can be used on the web and will be displayed."

     

    That's 8bit red + 8bit green + 8bit blue = 24 bit.

     

    And in my original post I did point out that -

    "... but, (and this must be remembered) download speed/time must also be taken into consideration as ..."

     

    As for high end cameras using 16 bit, these can now be used in some modern browsers, (but not all unfortunately) if they are converted to 'tiff', and that file format is used, (not much help x-browser I know,  ), but at least some browsers are now starting to support higher end images.

     

    PZ

     
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  • Currently Being Moderated
    Apr 4, 2012 1:46 PM   in reply to AdobeCoussini

    Hi

     

    You are correct in your examples, and which image format you use will depend on the quality and how you wish your graphics to appear on the web page.

     

    As a general rule, use jpg for photographic images, gif for simple graphics or images that do not require high quality display, (thumbnails for image galleries are a good example of this use) but if you wish to produce high quality graphics or use images that you will edit and save more that once or twice use png.

     

    The reasons for using png for graphics is not only the quality but png also supports true alpha channel, (this is why they have the extra 8 bits) also images using jpg will eventually have a poor image quality if they are edited then saved a number of times, (jpg uses what is known as lossey compression, meaning that every time you save them they loose some image data/detail), png does not have this problem.

     

    Don't limit yourself to 16 bits, but instead use the one that has the quality you require, also remember that you may have to consider the image file size when using any format, so as to achieve an acceptable overall page weight, (size of a web page including all images and other items such as css style sheets and javascript).

     

    PZ

     
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