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Old Nov 18, 2003, 7:20 PM   #1
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Default Am I resizing correctly? I think not

When I look at the pictures posted on some sites on the internet, or a good example is the picture of the day section here on Steves, I notice that the pictures look great for their file size. Now I know that obviously most of it has to do with good pictures being taken by good cameras, but even when I take a high res shot on my camera, and then make it small enough for emailing purposes, it loses a ton of quality.

Lets say I shrink a picture down to ~100k and around 8x8 or whatever so that I can email it, the picture looks like crap. Wheras I notice that small 60k pictures in the pic of the day section look great, just as good as the high res shot that would fill my computer screen when I am reviewing the pics i took.

I am doing something wrong when I resize them. I leave it at 72DPI because it is just for computer viewing, but there is something else that either I am doing or failing to do.

I usually use Photoshop6 to resize. I use Irfanview when I need to resize quickly and I dont want to wait for PS to start up and load all the plugins, but I notice that when I resize using Irfanview, they really look bad.

Can someone that is using PS or any program really, tell me what settings I should be applying in the image resize window in order to shrink both the size and filesize of my picturse, without sacrificing the quality of the shot?

Thanks
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Old Nov 18, 2003, 7:25 PM   #2
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i think most people resize to about 800x600 pixels to show here in the photos area. some are a bit smaller, some a bit larger. other than that i don't have a clue. can you maybe show us what you mean? display the original and a resized pic.

dennis
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Old Nov 18, 2003, 7:36 PM   #3
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Default Re: Am I resizing correctly? I think not

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Originally Posted by sir_snaps-a-lot
I use Irfanview when I need to resize quickly and I dont want to wait for PS to start up and load all the plugins, but I notice that when I resize using Irfanview, they really look bad.
Select the Lanczos Filter based option in Irfanview for best results. When you go to the resize/resample menu choice (under IMAGE), you'll see a box for "Resample-Better Quality". Make sure this is checked. Then select Lanczos Filter from the drop down choices.

Leave the DPI, etc., settings alone. Just pick a new size (640x480, 800x600, 1024x768, etc.), and let it resample using Lanczos.

Also, make sure you are not overcompressing the image when you save it.

When you use the "Save As" menu choice, you'll see a JPEG Compression Quality Bar come up at the same time. If you choose too much compression, you'll get poor quality results, too (it will always default to where you had it at last, so if you had it set for poor quality, it will still be there).

I use Lanczos in Irfanview for both upsizing and downsizing photos with great results.
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Old Nov 18, 2003, 11:22 PM   #4
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For most of the Photo of the Day pictures I simply use ThumbsPlus to downsize the original photo to somewhere around 640x480 or thereabouts and after resizing I apply Thumb's Sharpen Less filter to give them a little snap. I then save the new file at JPEG quality level 75-85 to get the file size to approx. 80KB or less.

Many graphic programs let you resize a photo smaller, the trick is to add a little sharpening after resizing or else the new image looks kind of blurry.

-Steve
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Old Nov 19, 2003, 1:07 PM   #5
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Quote:
I use Lanczos in Irfanview for both upsizing and downsizing photos with great results.
JimC--I've tried both that and B-Spline a number of times, comparing the results by using them on the same photo. My results are always just a bit better with B-Spline. Anyway, that's how I perceive them. Can you say why you've chosen Lanczos? What I'm wondering about is the possibility that each is good, but perhaps on different kinds of pictures. Any thoughts?
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Old Nov 19, 2003, 1:44 PM   #6
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I started using it after Mike Cheney went with it in QImage Pro (although they did perform some additional steps, optimizing the output to a specific printer).

You can see some comparisions at this page:

http://www.ddisoftware.com/qimage/quality/

However, I now understand the QImage Pro prefers to use Vector (but includes 7 interpolation schemes).

Personally, I've found that the Lanczos algorithms in the free Irfanview work fine for my needs, whether or not I'm resampling up or down.

I see no unwanted stairstepping, etc., even when downsizing large images using Lanczos. Likewise, I've also found it great for upsizing (especially when trying to print cropped 8x10's from lower resolution photos from an old Nikon Coolpix 950 I still own).

For my limited needs, there is simply not enough difference in them to worry about it, and Irfanview is fast to load compared to other products (not to mention that it's free).

Here's a comparison that I recently found, that you may be interested in, with three different photo types:

PHoto 1 - 1407 x 612 pixels interpolated to 9000x3915
Photo 2 - 2558x1809 interpolated to 8000x5658
Photo 3 - 2560x1704 interpolated to 9000 x 5991

http://www.americaswonderlands.com/d...erpolation.htm
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Old Nov 20, 2003, 12:29 AM   #7
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I now have Thumbsplus that Steve recommended and I have actually tried to fool around with Irfanview and the Lanczos filter a bit more with slightly better results. I am going to try a bunch of different configurations and see where I get the best results. I always used Photoshop to resize but I have a sh**load of filters installed on PS (most I should get rid of because I dont use them) so it takes a good 30-40 seconds to load the program and recognize all the plugins and I just do not have the patience to wait so I love the ease of Irfanview which loads instantly. I still have to try out that ThumbsPlus a bit more.

Also, Jim, that was an interesting article on interpolation you posted. I have never needed it yet but it may help me out soon. I wonder though, would it work for very small web based images? I have gathered hundreds of cool photos off the web in the past few years (of people mostly, cultural icons and such) in the hopes of one day printing these up (not huge, maybe 5x7 or so, give or take) and framing them and plastering a wall with them as a sort of art piece or framed collage (rather a collage of framed images). But I knew that these 40kb - 70kb pictures would never print out well so I have never done it. I am not too worried about quality as they would be on a dimly lit wall, but I just don't want too much pixelation. Do you think that this interpolation method would work for that concept? I wonder. What do you think? I mean, the images are small, and some of them are not great quality, but they are the best I could come up with as they are gathered off of the web and it would take years of searching to amass the same collection of images with a higher quality if I were to search so I really have no other option if I want to print these images up and frame them.

Tell me what you think.
Thanks.
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Old Nov 20, 2003, 10:00 AM   #8
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40kb - 70kb are most likely far too small for the print sizes you're looking at (or almost any print size, for that matter).

In addition to resizing, the images are also probably very compressed (hence, my warnings about making sure you're not using too much JPEG Compression when downsizing).

These sound like the images I am getting from my Sanyo SCP-8100 camera phone (very low resolution, very high JPEG Compression). They are barely viewable, much less printable.
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