Optimization of Image Resizing
I write this article because someone asked me how to keep the sharpness after resizing the size. He said that after resizing the size, the photo loss the sharpness. Later he said your photo still sharp although you’ve resized it. Well this kind of question is a common problem for digital photo. Reduce the size means reduce the quality isn’t it? it’s true ~ but even it’s true there always a solution for a problem hehe….
For this tutorial I use photo from Winter Sunshine album cover.
First let compare before and after resizing:
Original size / before resizing: (zoom@100%)
After resizing 25%: (zoom at 400% to compare the detail in the same area)
My opinion: You can see the original version always better than resize version so never delete your original photo, I know that maybe cost you many spaces of hard disk ~ but I think buy more hard disk is better than sacrifice my memory in every photos I took hehe…..
Back to the topic, so how to fix this problem?
In order to fix this problem you need to choose the way to resize the photo. I use Adobe Photoshop CS4 and when I want to resize the photo there are some option in image size dialog box that you can modify such as width & height of the result. Many people usually just modify the size and/or maybe the resolution but they almost forget another important option in that dialog box (see image below).
By the default Adobe Photoshop CS4 will choose the resample image as bicubic (best of smooth gradients). Actually it is a good option but if you resize the photo become small size (for website) that could be a problem. People maybe see your photo is not sharp although the original photo is not like that.
In my humble opinion, I like to set the resample image become bicubic sharper (best for reduction). I choose this one because usually I resize the image to small size. Depend on the condition maybe you can choose other such as bicubic smoother if you want to enlarge the image.
For some cases, I also admit that bicubic (best for smooth gradients) produce a better result because bicubic sharper make the line/edge become sharp edge, people may think you over sharpened the image. So now the choice is yours ~ you can use the method that you preferred most hehe…
Later maybe you also think why I don’t give comparison for each resampling method, so how I choose the best method for different kind of photo….. Well, if I write the comparison (for all the method) ~ you won’t try it by yourself hehe……
Other Note: When I wrote this article, I also noticed that my photo in this blog also have a problem in term of sharpness ~ you can see my photos (in every album) a little bit not sharp. Well it’s not because of wrong resizing way but that one because wordpress automatically resize the image (and reduce the image quality). I like to resize the photo become 900 pixel * 600 pixel but the size to be viewed in wordpress automatically resize to 700*466 (for other style or css maybe different). In order to see my photo in 900 pix * 600 pix, you need to click the photo and it will link to other page and you can zoom the photo (and you can see the sharp photo for sure hehe….).
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