Forum: Photography


Subject: Image Re-sizing

syntheticdreamer opened this issue on Feb 27, 2004 ยท 13 posts


syntheticdreamer posted Fri, 27 February 2004 at 7:24 AM

Hi everyone, I'm having problems re-sizing my images without distorting them slightly, it annoys me cos i take the shots with a resolution of around 2000x1800 pixels and have to resize them to like 800x600 but the image quality is greatly reduced. I try saving the files as TIF and then resizing them like that, then re saving them as JPG but still same problems. Anyone know what i should do? Thanks in advance. And thanks to misha for reminding me how usefull the forum is lol Cheers Chris


Wivelrod posted Fri, 27 February 2004 at 7:53 AM

I'm no expert, but the aspect ratio of a 2000x1800 image differs to that of a 800x600 image. Your image is probably going to be shrink somewhat in the horiztonal plane, and will of course look distorted. Try resizing to 800 X 720 and see if the distortion is still there. That image size is the same aspect ratio to your original image.


syntheticdreamer posted Fri, 27 February 2004 at 8:08 AM

yes that was just an example of size difference. When i resize they re-size in a % ratio but they always look distorted or blurred. There is a file type that when an image is shrunk it doesn't lose pixel information. I thought it was a TIF file but i still have the same problem. When you re-size a JPG image the file throws out pixels which it finds unnecessary. That causes a distortion. It just irritates me cos i have really crisp fine images but when i re-size them the quality is so badly damaged. I'm not gonna put up a 2000x1800 image on here cos like less than half of it is shown on the screen, well with most screen resolutions that is. Thanks anyway for the advise. Much appreciated. Greetz Chris


Wivelrod posted Fri, 27 February 2004 at 8:15 AM

The only other obvious thing I can think of then is the JPG comrpession setting (usally set when you save as JPG). If it's compressing to much your image can suffer quality wise, it kinda looks blurry. But that wouldn't explain the TIF file though!!! :| scratches head I'm outta ideas :P What software you using to do the resize?


syntheticdreamer posted Fri, 27 February 2004 at 8:19 AM

Microsoft photo editor lol =P That might be the problem :D I'll check it out later on PS, i don't have access to Photoshop right now, Thanks again. Cheers Chris


DHolman posted Fri, 27 February 2004 at 8:48 AM

Attached Link: http://www.irfanview.com/

This link is to a free image resizing program. I don't use it, but it may help you with your resizing. Let me also correct what I think are a few misconceptions you seem to have. First - Whenever you reduce the resolution of a digital image, no matter what you use, you will lose information. It's the nature of the beast. If you have a photo with 100,000 pixels in it and you reduce it by half to 50,000 pixels no matter what you have thrown away 50,000 pixels. The trick is that you want to reduce the image in such a way that visually it looks like there hasn't been any pixels thrown away or, in other words, that it's visually lossless. Second - I think you're confusing saving a file with resizing a file. If you save an image as a JPEG, there will be data loss (the JPEG format uses lossy compression) from the image. TIF is a lossless format, which means that it doesn't throw away data. These formats have nothing to do with resolution resizing. Third - Whenever you resize an image, you will almost always end up with a softer image that will need to be sharpened (whether reducing or enlarging). This is why you shouldn't sharpen an image until it's at the output size you want. Sharpening a photo more than once usually degrades the image and doesn't allow it to look as good as it could. For instance, when I post-process a photo, I turn off all sharpening in camera (or in the raw conversion). Once it looks the way I want I save it. I then resize it to whatever size(s) I need. Not until the image is in its final size do I then sharpen it. Hope all that made sense. Been up all night and I'm quickly losing the ability to make sense. -=>Donald

syntheticdreamer posted Fri, 27 February 2004 at 8:52 AM

Thank you very much. I'll also check out that link you left. Your advise is very much appreciated, thank you. PS sleep my friend it will do you good, i have just woken from a 3 day sleep, well almost three days, i was awake for 4 days straight the days before, damn that was tiring =P Chris


Michelle A. posted Fri, 27 February 2004 at 10:40 AM

Donald knoweth what he speaks... sleepy or not... I was also going to suggest sharpening as a final step before uploading.... I really noticed the softness in your last upload too.

I am, therefore I create.......
--- michelleamarante.com


syntheticdreamer posted Fri, 27 February 2004 at 10:55 AM

Yes, i fixed that since and finally decided to go with raven on straightening up the 'Urban Lightstream'pic. Thanks. I'll be going through my gallery and fixing the images before i uploaded my new ones in the coming days.


MGD posted Fri, 27 February 2004 at 12:43 PM

In M$ PhotoEditor, you can resize an image with or without distortion ... "Image" -> "Resize..." options are "Allow Distortion" and "Smooth" To keep the aspect ratio of the image unchanged, do NOT click "Allow Distortion" (the help system did not want to tell me what smooth means. -- you'll have to try it and see.) You can also adjust the image size by using "File" -> "Properties" adn changing the pixels per inch value. I don't know what side effects accompany that method.


Misha883 posted Fri, 27 February 2004 at 5:42 PM

Yipes! "Allow Distortion"? "Smooth"? Not very scientific... Certainly you do not want to change the aspect ratio, (well, usually not...). There are several calculations used for resizing. For most things "bicubic interpolation" works OK. Hopefully the Microsoft documentation will somewhere give a clue about what they use. After resizing, some sharpening is usually needed.


DHolman posted Fri, 27 February 2004 at 6:15 PM

Attached Link: http://www.wingimp.org/

I must have been tired. Didn't even notice what you were using to do your editing. Microsquish's PhotoEditor. Ewwwwwww. :) For those out there who don't want to spend the hundreds on Photoshop there is a free alternative. "Gimp" is a image manipulation program that started out on Linux. It is very much in the class of Photoshop. In fact, if you have ever used Photoshop you will be very comfortable in Gimp. They have now written Gimp for many different platforms including Windows, Unix, OS/2 and Macintosh. Go to the above link and check it out. You can download it for free from their download page. There are tons of tutorials for using Gimp on the web and many books have been written (though, of course, there's more stuff written for Photoshop). -=>Donald

MGD posted Fri, 27 February 2004 at 6:59 PM

@misha883 Why use distortion? ... For trying to emulate the painting style of Domenikos Theotocopoulos? @DHolman "... of course, there's more stuff written for Photoshop" ... True ... but there would be more written for it if only because it is somewhat counter intuitive. LOL