Resizing

[Charlie99]

Big question here. I was wondering, when I look at my pictures I see these sharp images. Then I go to resize them and they lose their edge. Do you see this too or do I need to run to get a new set of glasses?

When you resize your pictures to post on the board what do you use to resize and what do you resize to?

If you are downsampling (reducing the number of pixels) it is natural to lose some detail and sharpness.

When downsampling in Photoshop Elements 3.0, "bicubic sharper" seems to work a bit better than straight bicubic. PE3 also has a really nice "Save for Web" dialog that lets you preview and play around with different settings such as jpeg compression levels and the number of colors and dither types for GIF.

For web and slideshows I generally resample to 800 pixels high for both portrait and landscape modes. This results in 1024x800 or 600x800.

 

[justleesa]

I have PSE2...(

I resize them to 800x600 too...what level do you select? Scubaboard doesn't take the pictures that I set to 12, I have to go all the way down to 5.

 

[Charlie99]

I also notice that sharpend pictures have more noise after they are resized

Sharpening seems to work best when it is the very last action before printing or posting to web. Much better to downsample first, and then sharpen. I also find that what is good sharpening for display on monitor is too much sharpening for a print, so for this reason also, it works better to sharpen after resampling.

If the objectionable noise is in low contrast sky or water areas of the photo, then cranking up the "threshold" setting of the unsharp filter will help, but there you will always increase noise when sharpening.
If the noise is objectionable because of color artifacts, you can cheat a bit by using "luminosity" blending mode for the sharpened layer rather than "normal".

 

[Charlie99]

I have PSE2...(

I resize them to 800x600 too...what level do you select? Scubaboard doesn't take the pictures that I set to 12, I have to go all the way down to 5.

If attached to a post, I think the limit is 200K bytes. If you have a poorly focused photo, or a photo with a lot of rather blank background without a lot of detail, then it won't take a lot of compression to get it within the limit. You have to look at file size rather than just picking a compression setting.

 

[Moogyboy]

hey Leesa

Just thought I'd put in my $0.02 here as an experienced Photoshop user:

Using the Sharpen or Unsharp Mask filters can help somewhat if the resolution is high enough, but with low-res images it often just makes it look cruddy. What "sharpening" really is, as I understand it, is a kind of selective contrast expansion. It exaggerates the contrast between pixels or areas that are of a different brightness or color. The bigger the contrast in the original, the bigger the contrast change after you apply it, but of course when you use the Unsharp Mask you can force it. It doesn't make an image *truly* sharper, in other words, but is kind of an optical ilusion which only works well on really high-res images.

Remember that screen resolution is only 72 or 96 dpi. It may look smashing on screen, but when you blow that image up that all disappears, and you see every pixel, block by blocky block. All the Unsharp Masking in the world isn't going to make that go away--it can't replace information that isn't there to begin with. In fact it could well leave artifacts, like dark lines around the edges of objects, making it look like a screen grab from a poorly received TV show on a VHS videotape. And don't get me started on too much JPEG compression.

The way around this is to shoot at the highest resolution you can, avoid too much compression, and SAVE it as a master copy, so you can do Save As'es and resize to your heart's content without destroying your original. Shooting high-res may eliminate digital's advantage over film re: amount of exposure you can take without reloading, but your photos will look better in the end, and stand up better to resizing. It's better to start big and size down than to start small and try to size up. Give yourself plenty of wiggle room when it comes to resolution. Avoid too much JPEG. And use the Sharpen or Unsharp Mask filters sparingly. That's my advice.

Perhaps that's reiterating what someone else essentially said. But this is my own take. I hope this helps you.

cheers

Billy S.

 

[liberato]

Downsizing by itself should have negligible affect on apparent sharpness but the .jpg compression that is often part of the process of making an image size smaller and "web ready" can significantly affect sharpness. There is a dance of compromise that has to be done.

If an image reduced to 800x600 at a certain compression to attain a required file size doesn't look sharp you can try reducing the image size to 1024x768 with less compression (same file size let's say) and it actually may look better. Also, remember the compression loss is cumulative. Multiple .jpg compression saves of the same file will deterioate it.

A general question: Is .jgp also lossy to some degree if I select 100% or maximum size when saving? Will repeated 100% saves still deterioate a .jpg?

 

[pete340]

A general question: Is .jgp also lossy to some degree if I select 100% or maximum size when saving? Will repeated 100% saves still deterioate a .jpg?

I think 100% is still lossy, but only by implication. With JPEG 2000 (the newer version of JPEG) you have an option for lossless compression, which suggests that you can't do it under plain old JPEG. But I'm certainly willing to defer to someone with actual knowledge here. <g>

 

[RonFrank]

A general question: Is .jgp also lossy to some degree if I select 100% or maximum size when saving? Will repeated 100% saves still deterioate a .jpg?

Yes it CAN.

JPG is a compression algorithm and lossy. There are a few *LOCAL* changes that in general do NOT result in additioinal loss. They are flip and rotate. However ANY time the image is changed, and resaved, there will be some loss to the area that has changed, and in some cases the entire image.

Losses are reduced by using 100% on EVERY save, but make sure you use the SAME setting EVERY time, or all bets are off.

The best way to work jpg is to open the original, modify it until done, and save once. Another way some like to work is to convert it to a RAW or TIFF format, work that saving as often as desirable, and then convert back and save.

In PS with the back option there is really not a great reason to work jpg's as TIFF's, just don't save until you are actually done. For all practical applications, saving a few times at 100% is generally not going to result in a huge loss. However if you plan on printing big, save once if possible.

 

[RonFrank]

Big question here. I was wondering, when I look at my pictures I see these sharp images. Then I go to resize them and they lose their edge. Do you see this too or do I need to run to get a new set of glasses?

When you resize your pictures to post on the board what do you use to resize and what do you resize to?

Some better than others, but in general, very nice.

Had I seen some before posting, I likley would not have wrote a book in my first reply

Here are some thoughts about web display, and DOWNSIZING (which I did not realize that was causing the issue).

First loss of sharpness should be minimal when downsizing, however loss of image quality definately is there. There are a LOT of other factors involved here.

First is that most Web based applications are NOT color aware. Loss/Conversion of the color space can result in the image looking muddier as contrast and tonal variations maybe lost when the color space is shifted.

I'm not sure of PSE is color aware or not.

Another thing to consider is the application you are using to share images. Most gallary's that are not geared to photographers (if that makes sense) don't allow one to download or store very large images, and often they put images through their own compression to reduce the size of bigger images. I have not used ScubaBoards gallary, so I'm not sure how it works, but likely not much different than most as I NEVER see larger images.

So things you can try are:

* Shift the color space to sRBG if you are using Adobe RGB or some other color space.
* Sharpening should be the LAST thing you do before saving an image. Do NOT sharpen, modify, sharpen, modify more.... sharpen again...
* Find out the Scubaboard limit, and resize to EXACTLY that before uploading.

If you are comparing images on Scubaboard, and your's seem flat, or soft compared to others, maybe drop the photographer a PM and ask them how they process an image before uploading.

IMO your images are nice, however I'm guessing they are missing some of the punch that you see display them larger, or printing them. That's another thing to recognize, small images will have less impact by the nature of their size!!

 

[justleesa]

However ANY time the image is changed, and resaved, there will be some loss to the area that has changed, and in some cases the entire image.

Now when I work a pic I save it as a processed version in a new file. Go on and add my water mark, save it as a signed photo (new file again). I take that pic and resize it for the web and save it as a webpic (last new file). I am clear that is saving 3 times I have gone down 3 grades. Could this be the reason for my quality loss? is it just too many saves? And what about the one I worked on and didn't save? Does it lose anything for being opened and worked on? (hope this doesn't sound screwy)