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Preview and sharpening

Posted: Wed Nov 12, 2003 2:36 pm
by Huib
You advice to set the preview at 100%. But when I work with images of 400 dpi (90 Mb) the picture appears far to big on the preview. I have to reduce the size to 50 or 33%. Also the sharpening is much bigger in the preview then after.
With small images in Jpeg (400 kb), I don’t have any problem. How is this possible?

Posted: Thu Nov 13, 2003 12:31 am
by HaraldHeim
If you haven't set the zoom to 100%, then the sharpening intensity will appear slightly stronger or weaker. That's because at a smaller zoom only a fraction of all pixels can be taken into account for sharpening. Also at smaller zoom the sharpening radius has to be sized down which introduces inaccuracies.

I guess you mean that you can't see the whole image at 100% in the preview. Anyway, you still can look at different image parts by scrolling the image in the preview. It is more important to see the sharpening effect at 100% zoom than to see the whole image.

A future version of FocalBlade will have a resizable window. But even then if you maximize the FocalBlade window to the full screen, you won't see the full image if you are working on 90 MB images.

Posted: Thu Nov 13, 2003 1:03 am
by Guest
Set your preview at 100%, then put your mouse cursor on the picture and _right_ click and hold the button down and move the mouse around. You'll be moving your image around to view all of it's parts.

Harald is right. Even working in PhotoShop or Paint shop Pro, there's no way to see a large image 100 percent in one window. You have to drag it around to see it's various parts.


bill n

Posted: Thu Nov 13, 2003 9:40 am
by HaraldHeim
In FocalBlade 1.01 you can also hold down the ALT key and use the left mouse button to move the image in the preview.

Posted: Thu Nov 13, 2003 10:51 am
by Huib
I have always understand that to judge the sharpening of image you have to see the photo at your screen at the same size as the print. But in the preview of Focalblade, the image of 90 Mb appears 3 times bigger then the actual print will be. Is this correct?

I also find out some thing very strange. If I open an image 2900 dpi size 3,39 x 2,33cm and open this in Focalblade the image appears very big. I cancel without applying the effect. Without doing anything, the image is in PS changed in an image of 72 dpi 136,74x 93,73 cm. ?????????

Posted: Thu Nov 13, 2003 3:48 pm
by HaraldHeim
I just used an image with the same size and resolution (2900 dpi, ca. 3.3 x 3.5 cm) in Photoshop and applied Focalblade. I didn't notice that the image in the preview was bigger than the one in the imag window. Also, the resolution and size wasn't changed by Focalblade.

FocalBlade is a filter plugin and filter plugin can't change size and resolution of an image. So I'm not sure what else you do to produce that problem.

Maybe when saving that image, the dpi information wasn't saved with the image. So when you reopen it, your image applications assumes that it is 72 dpi. Might that be an explanation?

I assumed that you use Photoshop. Do you use another image application?

Posted: Thu Nov 13, 2003 5:15 pm
by Huib
I tried it with several tiff and jpeg images. As soon as the image has more or less then 72 dpi and I bring it into Focalblad following “cancel”, the image is bring back to 72 dpi. If I don’t ‘cancel’ but use the ‘Ok’ then nothing change with the dpi size.
So, when I have more then 72 dpi the photo appears bigger then the actual size in the preview.
I use only PS7.0 and Win 2000.

Posted: Thu Nov 13, 2003 9:35 pm
by Huib
Believe or not but the ‘Cancel” changes has gone after using some other plug-ins.
What still is, is the way the image come in the preview. An image of 2,4 x 3,6 cm / 2900 dpi comes in the preview like an image of 1 meter. I have to bring the view to 14%. Same thing for Color Washer.

Posted: Thu Nov 13, 2003 11:55 pm
by HaraldHeim
Huib wrote:What still is, is the way the image come in the preview. An image of 2,4 x 3,6 cm / 2900 dpi comes in the preview like an image of 1 meter. I have to bring the view to 14%. Same thing for Color Washer.

You probably have the image displayed at a small zoom rate (e.g. 12.5%)in Photoshop. Your 2,4x3,6cm/2900 image is 2740 x 4110 pixels large. So when you run FocalBlade and it switches to 100% zoom, you will only see a small fraction of the image in the preview.

You need to view it at 100% to get an accurate impression of the sharpening. Of course with such a large image the sharpening should also look more or less accurate at a smaller zoom rate.

Posted: Fri Nov 14, 2003 10:45 am
by Huib
Do you mean ( I don't think so) Harald that not the print dimensions in cm or inches gives the right size to judge but you have to judge the sharpness at 72 dpi?
100% view means that you look at the image at 72 dpi and it doesn’t matter in what dpi you print?

Posted: Fri Nov 14, 2003 12:35 pm
by HaraldHeim
You can accurately on screen how sharp a print will get. Some people recommend to set the image e.g. to 25% zoom if you print at 300dpi, but that is only an unpecise approximation. An image that looks sharp on screen may look soft in print and an image that looks oversharpened on screen may look just right in print. You have to do test prints if you want precise results. However, you can see at 100% zoom most accurately how the sharpening affects the image.

Of course you have to decide yourself which method fits you best.

Posted: Mon Nov 17, 2003 3:30 pm
by Huib
So, even if you print your photo at 300 dpi or more, you enlarge the image and look on you screen how it looks at 72 dpi. 100% means that you view the image at 72 dpi. :-?

Posted: Mon Nov 17, 2003 6:33 pm
by HaraldHeim
You can only view an image at 300 dpi if you printed it at 300 dpi and look at the print. I don't know of any software that can emulate the look of a 300 dpi print on a monitor. Would probably be nice to have one that does a more or less precise job for several printer types and models.