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Old 11th August 2002, 11:50 AM   #1
w00dy
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Lightbulb Smart Resize ... does it perform?

When I compared resizes of 1280x960 shots down to A6 taken with my Kodak DC240, Photoplus 7, which I use can't compare with Photoshop 6 which we use at work. I see Photoplus 8 now has "Smart Resize". Has anyone found this to be a significant improvement, is upgrade worth it?
 
Old 11th August 2002, 06:34 PM   #2
Martin Taylor
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Lightbulb Re:Smart Resize ... does it perform?

Hi

Are you comparing printed output, or on-screen quality? I suspect you mean printed output, or you wouldnt be talking about A6.

I think that old bugbear of dpi/resolution comes into this. I'm not sure what resolution you're printing at, but at say 300dpi, for a 6" x 4" print (A6-ish, I think), your image would need to be 1800 x 1200 pixels. That's an increase over your original, so the software needs to add extra pixels.

Maybe Photoshop is just better at adding extra pixels, then. (Edit: It ought to be, the amount it costs ...) I can't judge, because I don't have access to a copy. When you resize in PhP7, are you specifying the dpi resolution and the final printed size?

In both PhP7 and 8, the methods available for resizing are "Nearest pixel", "Bilinear interpolation", and "Bicubic interpolation". Serif recommend the last of these for increasing photo size, and I have to say the results are pretty good, particularly if you sharpen the image after the resize.

But I also just found that PhP8 has an undocumented extra method available - "Lanczos3 Window" ? at the top end of the quality slider.

By comparison, PaintShopPro has an actual selection for "Smart resize", which I suppose just chooses the most appropriate method for your image. PhP doesnt - you have to choose for yourself, despite what you saw

Martin
 
Old 12th August 2002, 05:32 AM   #3
Dale Cook
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Lightbulb Re:Smart Resize ... does it perform?

Smart Resize does exist in PhotoPlus 8 - for all downsampling (reduction in size), PhotoPlus 8 will anti-alias the image except when the lowest-quality algorithm is chosen. For increasing the image size there is still the flexibility of choosing a method. Our Bicubic Interpolation has tested as better than most, and the new Lanczos3Window interpolation is also effective when both increasing and decreasing the number of pixels in an image.

And I support Martin's comments about the pixel size of the image - it's impossible to effectively reduce a 1280x960 image to A6, it's comparing apples and oranges. A 1280x960 image can print to fit in an A6 area, but the 1280x960 image doesn't have a size in inches to start with so it shouldn't need "reducing". Instead, focus on the desired quality of the end result and work backwards - if anyone wants to print at 300 dpi quality then they will need 300 image pixels for each inch of the output. So, yes, a 6x4 inch print will need 1800x1200 pixels to be 300 dpi quality, for instance. And in that case I'd also support increasing the number of pixels, not decreasing. Bicubic or Lanczos methods should give excellent results that can stand up next to Photoshop output and grin wickedly.

Ta, Dale.
 
Old 12th August 2002, 06:50 AM   #4
Mike Keller
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Lightbulb Re:Smart Resize ... does it perform?

Dale

I like that "stand up next to Photoshop out and grin wickedly comment"...

True indeed.

Mike
 
Old 12th August 2002, 07:49 AM   #5
Toby Sharp
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Lightbulb Re:Smart Resize ... does it perform?

PhotoPlus's interpolation algorithms have always been superior to those of PhotoShop's, Paint Shop Pro's and PhotoPaint's. (Tests you can do at home will confirm this, if anyone is interested.) Now in PhP8, we have extended this processing to decimation algorithms which are used when reducing the image's size. We have also added a higher quality resampling kernel called Lanczos3 window, which is better (and slower) than bicubic resampling.

I'm not quite sure where "Smart" came into it. The user still chooses the quality of the algorithm from a slider in the resize image dialog box. If you want the best quality, just move the slider up to Lanczos3.

Because our image resampling is seamless, you don't have to think about whether you're increasing or decreasing in size, like you do with PSP. The same resampling algorithms (bilinear, bicubic, etc.) are applicable to both cases. Um, I guess that is quite smart...

I wouldn't trust PSP's smart algorithm too much, based on my tests. I seem to recall it just chooses between box filtering and bilinear interpolation based on whether the new size is up or down. Not too smart, and quite low quality. What if you expand the image in one dimension and reduce it in the other? What you really want in this case is decimation and interpolation simultaneously in different dimensions.

PhotoPlus 7 and earlier didn't have this functionality, so reducing images resulted in much lower quality output.

Regards,
Toby.
 
Old 12th August 2002, 07:58 AM   #6
John Vesey
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So, and to paraphrase a well-known advertisement:

"One day, all bitmap-editing software will be made this way"

John
 
Old 12th August 2002, 09:07 AM   #7
Martin Taylor
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Lightbulb Re:Smart Resize ... does it perform?

Hi all,

Thanks for the extra input - although I don't know yet whether we've answered w00dy's original question .

Martin
 
Old 12th August 2002, 09:40 AM   #8
John Vesey
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Lightbulb Re:Smart Resize ... does it perform?

Martin,

w00dy said:

>>Has anyone found this to be a significant improvement, is upgrade worth it?

I think that Toby's explanation goes some way to answering the first part of the question, although I personally haven't compared printed output from PhP7 and 8 (or indeed PaintShop Pro) to give an opinion. I don't have PhP7 installed anymore and don't fancy reinstalling it just for this

As for the last part of w00dy's question - I personally think that the extra features of PhP8 make the upgrade good value. I realise that there are a couple of "issues" that might be of sufficient importance to cause others to disagree

John
 
Old 12th August 2002, 12:53 PM   #9
Martin Taylor
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Hi, John,

I should have put that a bit more clearly - I really meant that it will be interesting to hear back from w00dy.

Martin
 
Old 12th August 2002, 03:13 PM   #10
Martin Taylor
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Lightbulb Re:Smart Resize ... does it perform?

Hi, Toby,

Tests I can do at home? What protective gear might I need?



Martin
 
Old 14th August 2002, 05:37 AM   #11
w00dy
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Lightbulb Re:Smart Resize ... does it perform?

Well, I've had a good play around with PhP7 now and can now get some far better results. I agree sharpening after resize does help a lot. The Resize wizard in PS6 automates that part of the process which saves time but PhP7 gets there in the end.

I think that I'll go for the upgrade to PhP8, my kids love the Serif stuff, particularly DP6.

Thanks for the comments on this thread, it's been a big help.
 
Old 15th August 2002, 08:08 AM   #12
Toby Sharp
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Lightbulb Re:Smart Resize ... does it perform?

Interpolation test:

Load the attached image chequer.bmp into a photo program. It's a 3x3 bitmap with alternating black and white pixels and no transparency. Resize the image to, say, 600x600 pixels. Different algorithms and different programs produce different results. You can compare the results subjectively. The correct results for bilinear and bicubic interpolation can be seen in PhotoPlus 7 or 8. Compare the results of other programs' output to see the difference. (I seem to recall the bicubic output from PhotoShop 5 is appalling!)

Decimation test:

Load the attached image rings.bmp. (This test image is due to graphics expert Ken Turkowski.) Resize it to, say, 128x128 pixels. Compare the results of different algorithms and different programs. If the image is properly anti-aliased, you will be able to count several clear concentric circles around the central ring. Between the sets of rings, there shouldn't be any 'ghosted' rings visible - just a gray area. Do the PhotoPlus Lanczos3 window algorithm to see how the results should look.

If you do these tests, you will see how certain other programs can compromise the fidelity of your images when resizing them.

Other interesting results involve resizing rings.bmp to other sizes, for example non-integer scale: 171x171, stretching scale: 128x512. Some programs cope with these cases poorly.

I have done all these tests and many more with various versions of PhotoPlus, PhotoShop, Paint Shop Pro, PhotoPaint and others.
I'm confident that PhotoPlus's resampling algorithms are accurate and correct for image resizing ( * ). Surprisingly, none of the other popular packages seem to be able to match this claim. See the attached comparsion document, resampling.html, for details.

( * ) Small print: The above discussion applies to space-invariant resampling only, such as in image resizing. Our bicubic interpolation is bicubic convolution interpolation, not bicubic spline interpolation. The quality of your resized image depends on the method of interpolation that you choose. Comparisons accurate at the time of writing.

Incidentally, this resampling technology is now used in PagePlus 8 PDF to ensure precision bitmap output.

Toby.
 
Old 15th August 2002, 10:08 AM   #13
Martin Taylor
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Lightbulb Re:Smart Resize ... does it perform?

Thanks, Toby - I wondered whether there was an objective way of doing the comparisons. I'll give those tests a try.

Martin
 
Old 25th August 2002, 10:29 PM   #14
Jim Dillman
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Lightbulb Smart Resize

Thank to W00dy for the query, & to Dale & Toby for VERY helpful response.

Jim, Ocala, FL Casioqv3000 PhP8
 
 

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