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DPChallenge Forums >> Tips, Tricks, and Q&A >> Best way to resize photos taken with my Canon 40D?
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 01/13/2008 05:37:15 PM · #1
I really like the Canon 40D I received for Christmas but I'm having a hard time resizing photos down to 640 pixels for the challenges (basic editing) without losing picture quality. I have never had this problem with any of my other cameras - I would resize down to 640 pixels on the longest side, sharpen using USM or Smart Sharpen and the picture would look fine. Now, with the bigger 10mp picture size with my 40D the pictures look great until I resize and then they just lose their oomph - they look okay but not as good as they did before resizing.

Last night I piddled around resizing a challenge entry with every way I could think with PS - bicubic, bicubic softer, bicubic sharper, nearest neighbor and bilinear. It just didn't resize down to 640 pixels without losing quality. If I resized to 800 or 720 it would look fine but not at 640.

Is there a better way to resize the large 10mp pictures? For challenge entries should I NOT use the largest available picture size on my 40D?
 01/13/2008 05:41:32 PM · #2
Don't forget that the new advanced editing rules allow for a maximum side of 720 from the old 640 pix and max filesize of 200k. Might help your reductions getting as mangled (I know a few of mine have been destroyed trying to shoehorn them into 150k).

N

Message edited by author 2008-01-13 17:41:46.
 01/13/2008 05:56:52 PM · #3
I use save for web or resize directly from lightroom.

What colourspace are you in when you try to resize? If you're using save for web you need to convert the colour space to sRGB before save for web. It's not done for you.
 01/13/2008 06:46:32 PM · #4
Ya, it's hard. Just a small 4x6 at 300dpi is at least 1800x1200. With 640 being a third of that. You loose a lot of detail going to 640.

Don't know what to tell you, except, print it at 8x10 and hang it on the wall. And don't get me started on those digital picture frames, some of the cheap ones ($100) are only 480x234. Less than dpchallenge.
 01/13/2008 07:17:08 PM · #5
Originally posted by cpanaioti:
I use save for web or resize directly from lightroom.

What colourspace are you in when you try to resize? If you're using save for web you need to convert the colour space to sRGB before save for web. It's not done for you.


It's not saving for the web that is giving me the problem. It's going from 3800 pixels on the longest side down to 640 for the basic editing challenge. Once the picture is actually resized I can save it for the web at 80% and still be just under 150kb so I'm not losing quality there - it's in the actual resizing from 3800 pixels to 640 on the longest side.

I was hoping someone would have some know some way of resizing that wouldn't be so destructive when you start with such a huge picture.
 01/13/2008 07:23:05 PM · #6
Sorry, I haven't found a good way either. I have found, however, that the quality loss is more noticable on some subjects and types of shots than others. I will be watching this thread to see if anyone has come up with an answer!
 01/13/2008 07:23:47 PM · #7
I resize directly from the native RAW converter with my 40D. Rather than have some major loss converting out of RAW I use the Canon software and that allows me to convert to JPG at whatever size I want. I choose the large size to the challenges largest allowable size and lock the aspect ratio. With that all done natively then I go into PS and save for web.
 01/13/2008 07:23:55 PM · #8
It don't have anything to with the large files from the 40D. I resize to 640 from my 5D and they look fine in most cases. Sometimes you just get one of those shots that just doesn't look good at 640.


01/13/2008 07:27:24 PM · #9
try USM at around 10%, 60px and fiddle with the threshold before resize... I just came across that technique for giving your images a bit more "omph" and was impressed at the result. Might be what you are looking for.

ETA - lmao - i forgot that it was on this site and this thread that i learnt that piece of info

Message edited by author 2008-01-13 19:30:47.
 01/13/2008 07:52:46 PM · #10
Try a fairly aggressive sharpening BEFORE resize and then do a bit of sharpening afterwards.
 01/13/2008 08:09:09 PM · #11
Another strategy to try... resize using bicubic to 2x the final size. So if resizing for Member Challenges then resize to 1440 (2 times 720) or for Open resize to 1280 (2 times 640. Now resize to the final size using Bicubic Sharper in one step. Now sharpen *very gently*.
As Leroy suggests, a little sharpening prior to resizing can help some images.
 01/13/2008 08:10:33 PM · #12
There was a thread about this subject a couple of months ago, and I now resize at about 500 pixel wide increments down to the finished size. It makes a huge difference in the finished size image. Just before the last 500 pix step, sharpen once again, then do the last resize.
Another thing to do is to strip off all the exif and fluff files that are with the challenge entry before doing the file size adjustment.

Message edited by author 2008-01-13 20:13:10.
 01/13/2008 08:14:20 PM · #13
Be careful doing incremental resizing when using "bicubic sharper." You can wind up with sharpening halos.
 01/13/2008 08:34:35 PM · #14
Thanks, everyone, for the ideas - I will try all of these things to see if it helps.

I've notice, too - that some pictures are just worse than others when you resize.

I'm almost embarrassed to say - I've never taken any pictures in the RAW format - I always use JPG. I've got to get started using RAW and seeing how different it is.
 01/13/2008 08:47:17 PM · #15
Originally posted by Sammie:

I'm almost embarrassed to say - I've never taken any pictures in the RAW format - I always use JPG. I've got to get started using RAW and seeing how different it is.


I'm willing to bet most of your problem lies here. RAW doesn't have any in-camera sharpening and are rather soft to start. In such, you do need to do some pre-sharpening before down-sizing the image.

You can do it in RAW conversion or in Photoshop. A lot of people want to save any sharpening as a final step.
 01/13/2008 08:57:15 PM · #16
One thing nobody is mentioning is that extreme wide angle photos don't resize well at all. They are super-detailed at a very fine level, and you lose a LOT of resolution when you resize them. Then you're forced to sharpen aggressively to try to retain detail, and then the JPG quality drops way down when you try to go under 150 Kb, and it's just a mess. It's something we landscape photographers deal with all the time that the studio photographers, with their plain BGs, don't have to worry about.

R.
 01/13/2008 08:58:34 PM · #17
Originally posted by Bear_Music:
One thing nobody is mentioning is that extreme wide angle photos don't resize well at all. They are super-detailed at a very fine level, and you lose a LOT of resolution when you resize them. Then you're forced to sharpen aggressively to try to retain detail, and then the JPG quality drops way down when you try to go under 150 Kb, and it's just a mess. It's something we landscape photographers deal with all the time that the studio photographers, with their plain BGs, don't have to worry about.

R.


Very true, us portrait photogs often try to LOSE detail :-D
 01/13/2008 08:59:44 PM · #18
Originally posted by Sammie:
Originally posted by cpanaioti:
I use save for web or resize directly from lightroom.

What colourspace are you in when you try to resize? If you're using save for web you need to convert the colour space to sRGB before save for web. It's not done for you.


It's not saving for the web that is giving me the problem. It's going from 3800 pixels on the longest side down to 640 for the basic editing challenge. Once the picture is actually resized I can save it for the web at 80% and still be just under 150kb so I'm not losing quality there - it's in the actual resizing from 3800 pixels to 640 on the longest side.

I was hoping someone would have some know some way of resizing that wouldn't be so destructive when you start with such a huge picture.


I use save for web to do the resizing.

Anyway, if you're resizing before save for web then you need to sharpen afterwards, not just rely on the algorithm within the resize window.

Message edited by author 2008-01-13 21:01:12.
 01/13/2008 09:15:44 PM · #19
I scale to 75% a whole bunch of times. It seems to degrade the image less than bigger steps.(Could be wishful thinking on my part). Final re size step I type in the size I want. Then I save for web and use the "optimize to file size" option.


Message edited by author 2008-01-13 21:20:34.
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