Resizing

[Kaye]

I'm a little confused here again and hope you computer guys can help me. The following two photos were taken with Nikons. The first the D40 and the second with my D90. When I went to upload them onto my nephews myspace, the D40 pics went on with no problem and looked great. I had to resize ALL of the photos from the D90 before I could upload them and they don't look as sharp as the D40 photos on his myspace. Can someone please explain this to me. Both were taken in Auto mode.



Camera: Nikon D40
Exposure: 0.001 sec (1/1600)
Aperture: f/5.6
Focal Length: 135 mm
Focal Length: 138.5 mm
ISO Speed: 400
Exposure Bias: 0 EV
Flash: No Flash
File Size: 2.4 MB



Camera: Nikon D90
Exposure: 0.001 sec (1/2000)
Aperture: f/5.3
Focal Length: 220 mm
ISO Speed: 400
Exposure Bias: 0 EV
Flash: Auto, Did not fire
File Size: 490 kB

[Grumby]

My initial thought is that the D40 is a 6MP camera wheras the D90 (you lucky so and so) is a 12MP camera. Don't know anything about mySpace, but if they have an 'image size' limitation, as opposed to a 'file size' then this may be the problem (looking at the data attached to the 2 images you provided, I see that the D40 image filesize is 2.4Mb whereas the D90 image is only 1/5th as much - is that D90 filesize what it was AFTER you resized it?)

Not sure if your question is around why you couldn't upload in the first place, or if it is about the quality issues you have with the resized version...

If the former...

If that is the resized filesize, what was it before?
The format you save images in has an influence - RAW files are huge, and then you usually get 3 flavours of JPG - high medium and low resolution - each of these will also impact the size of the resulting file, with the jump from medium to high having quite a profound affect on the resulting filesize.

If the former...

I can only suggest playing around with the options on your software you use to resize. Tools like Gimp and Photoshop offer many different mechanisms for resizing, each of which uses different algorithms to merge/insert pixels, and smooth out edges. What software did you use?

Grumby

[Kaye]

Grumby: Thanks for responding. I'll try to answer your questions the best I can.

Both pictures were cropped before I uploaded them to Flickr. I also find it odd that the D40 photos look sharper on my screen, but the D90 photos print better. Pixels, you think?

The original pictures that I take with the D90 on Jpeg/Fine/Large are the ones that Myspace will not allow me to upload until I resize them. I took a pic last night in the house. Resized it and looked at both on a Wal Mart viewing program I have (the fastest one to just see what would happen). I could not believe how bad the resized photo looked.

I have been using Corel Snapshot Plus to resize them.

Tonight I went out to a scrimmage game and took some photos in Jpeg/Fine/Medium. Myspace allowed me to upload everyone without resizing the first one. And although I would still like a little sharper photo on myspace (look good on flickr), I'm beginning to think the D90 is somehow just to much for myspace. I know that sounds silly, but I can't make it make sense any other way.

Thanks again for your help.
Kaye

[morts]

I'd get a copy of GIMP (free) and play with the resizing settings in there. As Grumby said, there are a myriad different algorithms for resizing photos and some work better than others. I'd suggest playing with that!

[Grumby]

Hi Kaye,
OK - so let's do an experiment... get a 6MP D40 image and a 12MP D90 image that are both taken at the same setting - e.g. JPG Fine. Next CROP them both to a size that can be uploaded to mySpace (don't resize - just crop, and crop them both to the same size), and then compare them both on mySpace and your screen, etc. In theory - these should both appear the same quality. If not, then I don't know what's going on (but I LOVE mysteries ) If they do appear the same quality, then we can move on from there...

I guess the next thing to consider could be the fact that the D40 images didn't actually need resizing, whereas the D90 images did. The fact that you have had to try and squeeze 12 million dots into 6 million spaces means that there will be some loss of quality. If I was UPsizing an image, I'd do it in small chunks - i.e. instead of a big bang 100% increase, I'd do it repeatedly by 10% each time - try it yourself and see the difference. Perhaps the same loss of quality applies if you are DOWNsizing an image - I've never really put it to the test...

Give these a try, and let us know the results
Grumby

[Kaye]

I have to get my friend over with the D40 to give this a try or may wait until next Saturday for the next Softball tournament. I always use both cameras when we are at one. But I will try it. Although I do have a folder with some of the D40 pics in it, but I think your idea of them being the same picture, same everything is the best way to try and figure this out. Will save this and let you guys know what happens when I give it a try.
Thanks

[Grumby]

No problem Kaye. I'm half computer-nerd, and half Vulcan - so every problem gets broken down into logical steps in my world (frustrates the hell out of my wife sometimes, as she has more of a 'jump right in' approach).

The two images don't have to be identical, but if you can start off with both cameras on the same settings for technical comparison, and the same subject/lighting/viewpoint for a visual comparison, I think we'll pretty quickly get to the bottom of it.

When you get the two cameras side-by-side to take your source images, can you take some comparison images at all three JPG qualities while you are at it. The differences you are seeing may be related to the JPG compression rates. The middle quality commonly uses something like an 80-85% compression rate, which means that if your original was at that quality and then you resize it, you've already lost 15-20% of the information even before you start. Our experiments may reveal that resizing a medium quality original does not give such good results as resizing a fine quality original.

BTW - make sure you keep all the originals safe when you start playing with the cropping and resizing experiments, then we can go back to square one any time we need to.

Good luck,
Graham.

[Kaye]

Thanks Graham. Will find out next Saturday after the tournament. I must admit it is weird. Get back with you later.

[sk66]

The only part of this that throws me is that you say the d40 images look better on your screen but the d90 images print better....look better after uploading or before? look better at 100% or at a given size?.......apples to apples...

The d90 images have to be resized due to file size limitations....even after resizing there is probably some compression going on in the upload/view process which is degrading quality.

If you were to simply downsize the d90 images to the same size as the d40 they would look better....it's just a fact that images look "better" smaller....out of focus and grain etc is less noticeable... Same is true in printing...print a d90 image at 8x10 and a d40 at 8x10 and the d90 image is going to look better due to the "downsizing"...