JPEG Compression for web
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Gerald Corbiere
JPEG Compression for web
Using PhotoImpact XL SE, I have a number of photos I am trying to compress for faster downloads on my website. For the most part it seems I can't compress smaller than 175KB, however, on a couple occasions, I was able to compress down to 20KB, and once down to 2KB. The source files are all similar in size and features. Any idea why some don't compress like the others? Thank you for your help.
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VT Photog
The reason some photos will compress more than others is mostly due to the amount of detail in the picture. A clear, blue sky will give a smaller file size than trees and grass. (same dimensions and quality level)
If you are having trouble reducing to a given file size, you can try reducing detail by using one of the blur tools. Sometimes, the artifacts from sharpening or previous jpeg compression, are seen as details by the software. When this is the case, using Gaussian blur, or averaging at 2 pixel radius will help a lot.
If you are having trouble reducing to a given file size, you can try reducing detail by using one of the blur tools. Sometimes, the artifacts from sharpening or previous jpeg compression, are seen as details by the software. When this is the case, using Gaussian blur, or averaging at 2 pixel radius will help a lot.
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kingonlineuk
big files -- camera info
I have another theory.
Many digital cameras store information about the picture along with the image, and the bigger the camera usually the bigger the information.
I took a picture on my Nikon D70 with the aim of making a small 365 by 100 pixel graphic for our web site.
After editing, the file was saving from PhotoImpact as 45K: far too big and suspiciously big at that.
So I clicked: Adjust > Convert data type > 48 bit RBG True Colour.
Then I clicked: Adjust > Convert data type > RBG True Colour (24 bit) (no dither).
Then I used “save to web” again.
This time the file saved at around 7K.
I’ve emailed Ulead suggesting that there needs to be an option in “Save to Web” to strip the image of all unnecessary clutter, such as the photo’s data and thumbnails of earlier versions.
I’ve done this with several photos being saved for web site and the file usually reduces to a third or less of the size it would be without this odd process.
David King, Web Team, Dudley College.
Many digital cameras store information about the picture along with the image, and the bigger the camera usually the bigger the information.
I took a picture on my Nikon D70 with the aim of making a small 365 by 100 pixel graphic for our web site.
After editing, the file was saving from PhotoImpact as 45K: far too big and suspiciously big at that.
So I clicked: Adjust > Convert data type > 48 bit RBG True Colour.
Then I clicked: Adjust > Convert data type > RBG True Colour (24 bit) (no dither).
Then I used “save to web” again.
This time the file saved at around 7K.
I’ve emailed Ulead suggesting that there needs to be an option in “Save to Web” to strip the image of all unnecessary clutter, such as the photo’s data and thumbnails of earlier versions.
I’ve done this with several photos being saved for web site and the file usually reduces to a third or less of the size it would be without this odd process.
David King, Web Team, Dudley College.
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keenart
I change my photos from 24 bit to 256 colors, then compress to JPG 100 %, then compress again, and then again until the JPG gets as small as possible.
Mind you you want to check the result on the Web before you use the image in its final form as sometimes the image can get pretty grainy.
You can always use a very small compressed image, and then create a second better larger image to click on as a blowup.
Mind you you want to check the result on the Web before you use the image in its final form as sometimes the image can get pretty grainy.
You can always use a very small compressed image, and then create a second better larger image to click on as a blowup.
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heinz-oz
First I would resize the image to a smaller format. Depending on what size you want to display at. For web use in good quality I would make it 400 or 500 pixels wide and use the display resolution of 72 pixels/inch.
For thumbnail size pictures I would reduce it to not more than 60 or 80 pixels wide.
Saving that as a jpg with 80% compression gives you a small file size at reasonable to good quality.
If you want to work with images in PI, I would suggest to take the free beginners workshop on the PI resource center (http://www.pircnet.com/). They will teach you the basics of PI and it costs you nothing. Just your time, and you are waisting plenty of that, trying to use a complex software, without understanding the basics of digital compression/imagery.
For thumbnail size pictures I would reduce it to not more than 60 or 80 pixels wide.
Saving that as a jpg with 80% compression gives you a small file size at reasonable to good quality.
If you want to work with images in PI, I would suggest to take the free beginners workshop on the PI resource center (http://www.pircnet.com/). They will teach you the basics of PI and it costs you nothing. Just your time, and you are waisting plenty of that, trying to use a complex software, without understanding the basics of digital compression/imagery.
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keenart
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heinz-oz
Have you printed the same image at 72 and 96 pixels? After all, you do not design your web site for printing, do you? The difference between the two resolutions is, at best, marginal. The question was in relation to small file sizes, if I remember correctly. If I wanted to have something to print in reasonable quality, I would use at least a resolution of 160 to 180 pixels/inch. Furthermore, the image resolution only affects the size at which the image will print, not the quality. If you compress an image to the max in order to get the smallest file size, it does not matter anymore. The quality is going to be low.keenart wrote:Yes 72 dpi is the standard for Monitor viewing of Web graphics.
However, If you expect your Web page to be printed, I would suggest 96 dpi as the minimum reduction in resolution. An Industry wide excepted parameter, it gives your image a better print quality than 72.
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keenart
72 vs 96 dpi is relative to your Web Design, graphic needs, and the type of Viewer you wish to reach, Laptop or Desktop user. I won’t go into detail, but, will give you a few pointers, as everything is Important in designing and reaching your audience through your Web Page.
What type of Audience do you want to reach?
How fancy do you need to design your Web Page to attract attention, in relation to your product or service? PI has some awesome graphics for this.
What size and location of the Web Page are you to design and for what resolution?
Laptop users rarely printout anything, they almost always Bookmark, their screens are usually very small and therefore, 72 dpi is fine for this audience.
Desktop users, rarely Bookmark, or even know how to Bookmark, and when they want to retain the information from a Web site, they printout a copy of the Web Page. Desktop screens are usually large 17 to 19 in, 96 dpi is better for this audience.
Printers printout at various quality levels, Quick or Economy to Laser quality. In Economy mode, which most Desktop users use, 96 dpi will give you a good quality printout in relation to the dimensions of the graphic on your Web Page and still give a quick Load time for the Page. Otherwise, some large graphics at 72 dpi must be printed at higher quality to get an acceptable viewing image. A waste of Ink, use your forethought in designing your Web Page. I always included a Print Button on my Web Pages, as many people still don’t know how to use print.
Another method is to create a very Low Resolution, highly compressed Graphic, for view on your Web Page, and then Link to a Secondary Image of substantially higher Quality. This allows interested parties to view your graphic up close or printout the graphic for later reference. Some people do this just to be able to compare color schemes with your product in relation to their needs, a sometimes important capability.
You can call 72 vs 96 a matter of Preference; I call it a matter of Design Necessity.
As far as Prints go, 133 dpi is Magazine Standard, 150 to 170 is Art Print Standard. I have always used 160 for small Art Prints and 180 for very large Prints. The reason is because I paint in a very small size at high resolution, 3 in x 4 in x 760 dpi allowing me to paint quicker. This allows me to resize at any dimension or resolution later, depending on the look of the Art Work in relation to the Final Output Size. Some Prints in relation to the subject matter look good in as a small Print and some look better in a larger Print. I like to have the choice.
I use PI 10 for creation of Art Work and Adobe Photoshop for all of my Printing.
What type of Audience do you want to reach?
How fancy do you need to design your Web Page to attract attention, in relation to your product or service? PI has some awesome graphics for this.
What size and location of the Web Page are you to design and for what resolution?
Laptop users rarely printout anything, they almost always Bookmark, their screens are usually very small and therefore, 72 dpi is fine for this audience.
Desktop users, rarely Bookmark, or even know how to Bookmark, and when they want to retain the information from a Web site, they printout a copy of the Web Page. Desktop screens are usually large 17 to 19 in, 96 dpi is better for this audience.
Printers printout at various quality levels, Quick or Economy to Laser quality. In Economy mode, which most Desktop users use, 96 dpi will give you a good quality printout in relation to the dimensions of the graphic on your Web Page and still give a quick Load time for the Page. Otherwise, some large graphics at 72 dpi must be printed at higher quality to get an acceptable viewing image. A waste of Ink, use your forethought in designing your Web Page. I always included a Print Button on my Web Pages, as many people still don’t know how to use print.
Another method is to create a very Low Resolution, highly compressed Graphic, for view on your Web Page, and then Link to a Secondary Image of substantially higher Quality. This allows interested parties to view your graphic up close or printout the graphic for later reference. Some people do this just to be able to compare color schemes with your product in relation to their needs, a sometimes important capability.
You can call 72 vs 96 a matter of Preference; I call it a matter of Design Necessity.
As far as Prints go, 133 dpi is Magazine Standard, 150 to 170 is Art Print Standard. I have always used 160 for small Art Prints and 180 for very large Prints. The reason is because I paint in a very small size at high resolution, 3 in x 4 in x 760 dpi allowing me to paint quicker. This allows me to resize at any dimension or resolution later, depending on the look of the Art Work in relation to the Final Output Size. Some Prints in relation to the subject matter look good in as a small Print and some look better in a larger Print. I like to have the choice.
I use PI 10 for creation of Art Work and Adobe Photoshop for all of my Printing.
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Masami
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keenart