How to reach fine quality with less filesize
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Joined: June 23, 2004
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Location: Nasaretin Nakkikioski

How to reach fine quality with less filesize
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Posted on Fri Aug 27, 2004 5:19 pm
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This is how I usually edit my pics before submitting them.

I use Adobe Photoshop to do this:

1.) Open the picture (File-Open)
2.) Crop the image if necessary (e.g. with Rectangular Marquee Tool)
3.) Save the image as .jpg format (File-Save as)
4.) Open the image as .jpg format (File-Open)
5.) Change the image to reasonable size (Image-Image Size)
6.) Save the image for the Web (File-Save for Web). At this point you can adjust the image quality (Note: Keep watching the image filesize at the same time you do that. It can't be more than 100 KB).

Here is an exaple one of the pictures I've submitted here (original filesize: 1,312 MB, Current filesize: 41 KB):

Joined: September 26, 2002
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Posted on Sat Aug 28, 2004 6:45 am
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Too big for posting to the board, though -- please(!) keep images below 400 pixels in width if you want to post them as inline images.

If you believe that your image will suffer because of it, make two copies - one full-size, one thumbnail - and link one to the other by surrounding the img tags with a url tag like so:

Code:

[url=http://www.someserver.com/full_size_image.jpg][img]http://www.someserver.com/thumbnail.jpg[/img][/url]


Of course, for submitting to the gallery, the server automagically creates the thumbnail image for you.


"If 50 million people say a foolish thing, it is still a foolish thing." ? <i>Anatole France</i>

Joined: May 10, 2005
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Posted on Sun May 29, 2005 12:10 am
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That thing looks like a very painful flail.

I usually just reduce the colors to 216 and make all my web pics 28 ppi. I find that Paint and a little care in size go a long way when you are Photoshop-less.

Joined: September 26, 2002
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Posted on Tue May 31, 2005 6:40 am
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This is a FAQ.

Grab a copy of IrfanView, a free, lightweight image mangler.

All the basics you need to mangle an image for the web are there..

Step 1, remove (crop out) anything that doesn't enhance the value of the image. In the image above, you could easily have cut out a half inch from the top and sides without detracting from the image.

Step 2, Decrease the color depth to a lower value. When you do so, it'll ask you what kind of dithering you want. Always select "Floyd-Steinberg" - that's not the one that throws speckles all over the place, it actually does a really good job.. (I decreased the color depth on a sample image, and it lowered the uncompressed size by 65%)

Then, if anything more is needed, (look at the status bar at the bottom, it'll tell you the uncompressed image size) you can lower the jpeg quality - jpeg compression is lossy, so you can adjust as much as you like.. 60 and 80 percent look really similar imho. Just don't save at 60% and expect to be able to mangle it more afterward. Wink


"If 50 million people say a foolish thing, it is still a foolish thing." ? <i>Anatole France</i>

Joined: February 15, 2002
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Posted on Tue May 31, 2005 5:57 pm
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Actually, decreasing the color depth can cause the JPEG algorithm to generate a larger file size for a given quality. I tend to perform a "Blur" operation (.1 to .25 pixel radius) before saving as a JPEG - it gets a little extra compression with virtually no difference in the finished product.

If saving a line drawing (such as something sketched in Paint) or an IGP inlay, DO NOT USE JPEG!!! GIF and PNGs are your friends in this case. PNG will often create the smaller file, but some discussion board software does not like inline PNG's, so you are probably safer saving as a GIF. For saving in GIF and PNG8 formats, you SHOULD decrease the color depth before saving.


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Joined: September 26, 2002
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Posted on Thu Jun 02, 2005 12:39 am
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Zlosk wrote:
Actually, decreasing the color depth can cause the JPEG algorithm to generate a larger file size for a given quality.

If you use "standard" dithering (error diffusion) this is certainly the case, but more often than not, using Floyd-Steinberg dithering will (or, I should say, has in my case) dramatically decreased the final file size.

And I absolutely agree with Zlosk about line drawings.


"If 50 million people say a foolish thing, it is still a foolish thing." ? <i>Anatole France</i>

Joined: February 15, 2002
Posts: 397
Submissions: 10

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Posted on Thu Jun 02, 2005 3:58 am
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Hmmm. I've never had any type of dithering help with JPEG compression, but I'll give the Floyd-Steinberg a whirl.


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Posted on Thu Jun 16, 2005 1:30 am
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Dithering isn't in the compression, it's in the resampling of the colors to decrease the color depth.


"If 50 million people say a foolish thing, it is still a foolish thing." ? <i>Anatole France</i>

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