| Author | Message | ||
     J. Royal New member Username: Tipicanu Post Number: 65 Registered: 05-2003 |
I've been resizing a lot of images for the web lately and have been unhappy with the softness that has resulted from the resize transformation in PWP (most apparent in scenic shots with a lot of detail). I've switched to Irfanview for this function. I'm curious as to how PWP can show the full size image very crisply when displayed at 1:3 for example, but can't give me near that result when I resize to that same size. Even with bicubic interpolation and 100% sharpening, the image is very soft (btw, no visible difference between 0% or 100%). So much detail seems to be lost that further sharpening can't bring it back again without introducing artifacts. When I resize the full image in Irfanview using the same dimensions, it is nearly an exact match to the 1:3 display by PWP of the full image. I've tried all of the interpolation methods and none of them are satisfactory. Any thoughts on why this may be happening or what I may be doing incorrectly. I hate to go outside of PWP to do this. Thanks, Jeff | ||
| David J. Bookbinder New member Username: Dbookbinder Post Number: 128 Registered: 09-2002 |
I've noticed this, also, and tend not to use PWP for resizing. I'm figuring it's a flaw in the libraries used for this purpose and hope it will be corrected with a later release. | ||
| den Unregistered guest |
This sounds very similar to some concerns I had also....and there was no real resolution except larger files sizes... http://www.dl-c.com/discus/messages/2/5420.html?1112765509 I will take a look at using IrfanView.... thank you. | ||
| J. Royal New member Username: Tipicanu Post Number: 66 Registered: 05-2003 |
Den, what you mention in that thread does sound similar. However, file compression was thrown into that mix. The softness that I'm seeing is definitely coming from resize as I see the resized image and the 1:3 display of the original side-by-side in PWP and the 1:3 display is much sharper (and the result that I want from resize). I can't get it no matter what I do. Perhaps your problem was with resize after all? hmmm. Enjoy the weekend. | ||
| Hugh Croft Unregistered guest |
Respectfully, the resizer does need some improvement . | ||
| Jonathan Sachs Board Administrator Username: Admin Post Number: 2404 Registered: 08-2002 |
The sharpening slider in Resize produces very subtle results - for sharpen resizes one pass of the Sharpen transformation ususally works well. Jonathan Sachs Digital Light & Color | ||
| Mel Davies New member Username: Chilterns Post Number: 10 Registered: 11-2004 |
Jonathan. Is that assuming an already sharpened image you are resizing from and using the default sharpening of 16.7 percent. Is the sharpening in Resize, USM? | ||
| Jonathan Sachs Board Administrator Username: Admin Post Number: 2405 Registered: 08-2002 |
Yes the default sharpening of 16.7 percent in Resize's Bicubic resampling is the standard amount, but when downsizing a lot the image can start to look soft as many pixels in the original image are being averaged to produce each pixel in the output image. The recommended way to sharpen up the result is to use Transformation/Sharpen with the Sharpen option, possibly reducing the Amount setting if the result is too harsh. Jonathan Sachs Digital Light & Color | ||
| J. Royal New member Username: Tipicanu Post Number: 68 Registered: 05-2003 |
Thank you for the reply Jonathan, using Transformation/Sharpen with the Sharpen option at about 40% does do the job. Does this imply that this type of sharpening is built-in to the resize functions of other applications which yield shaper results with the same interpolation method? If so, I can see why you would want PWP to be conservative and leave the sharpening up to the user. If not, then perhaps there is a problem with the implementation of these methods in PWP. Also, can you explain why the 1:3 display of an image in PWP is much crisper than the resized image of the same pixel dimensions (regardless of whether or not antialiasing is on/off)? This doesn't make sense to me. I don't mean to complain, I'm just curious how this works. Thanks again. -Jeff | ||
| Jonathan Sachs Board Administrator Username: Admin Post Number: 2406 Registered: 08-2002 |
Yes, either the others have built it in or there is a problem with PWP. The integer resizing used in displaying images is much cruder than the algorithm in resize. Jonathan Sachs Digital Light & Color | ||
| David J. Bookbinder New member Username: Dbookbinder Post Number: 129 Registered: 09-2002 |
Jonathan, one thing that's not clear to me in this discussion is whether you believe the resizing transformation, when making an image smaller, is adequate as is. If not, would it be possible to build the Transformation/Sharpen transformation into the resizing algorithm, so that resizing and sharpening can be done in one operation, rather than using the sharpening that is currently built into Resize? | ||
| Jonathan Sachs Board Administrator Username: Admin Post Number: 2407 Registered: 08-2002 |
To the best of my knowledge it is working correctly, but I am not totally certain. Sharpening is only needed when downsizing and then in different amounts depending on how much the image is being reduced so it is not obvious how much sharpening to build in. Jonathan Sachs Digital Light & Color | ||
| David J. Bookbinder New member Username: Dbookbinder Post Number: 130 Registered: 09-2002 |
What I had in mind was building in the sharpening algorithm used in Transformation/Sharpen instead of the sharpening algorithm currently used in the Resize transformation, whose effects seem to be very minimal. Then, for instance, resizing and sharpening could be a one-step operation, with the sharpening adjusted to the user's taste, rather than a two-step operation. Just my two cents. - David | ||
| Jonathan Sachs Board Administrator Username: Admin Post Number: 2408 Registered: 08-2002 |
I understand, but the two sharpening features are doing something mathematically totally different. I will consider adding post-sharpening as a resize option for future versions. Jonathan Sachs Digital Light & Color | ||
| Elie Dinur New member Username: Elied Post Number: 57 Registered: 07-2003 |
Jonathan If you do that it would be good to have preview possible in resize also. Elie | ||
| Jonathan Sachs Board Administrator Username: Admin Post Number: 2409 Registered: 08-2002 |
Indeed Jonathan Sachs Digital Light & Color | ||
| Andreas De Troy New member Username: Dreticus Post Number: 14 Registered: 08-2002 |
ImageMagick (a free program) has a good reputation among experts for resizing images, but it's not so easy to use in my opinion. |
