Relative zoom calculation: a drawback

[David McA]

Old zoom function better for me

I use IV as default image editor. Among many uses is to preview the images taken with my digital camera. To get a good idea of how the image would look if printed or resized for screen use, I used to be able to view at 50%.

50% is by far the best scaling, giving the lowest resizing artefacts such as stepping in diagonals.

Now, I can't do this without actually resizing the image (via ctrl+R > alt+H > Return) and of course this is lost if I navigate to another image.

Also as the scaling is now random, it's not easy to compare 2 images (via 2 instances of IV) at the same scale if they have different original dimensions.
e.g. comparing the output from 2 cameras


If things are to be changed, better to have a series of fixed sizes
e.g. 10%, 25%, 50%, 75%, 100%, 150%, 200%, etc

A real step backwards for photographers.

Regards,
David

[Bodiniusz]

4.10 - sequencial Zoom In misses 100%

When Zooming in (by pressing '+'), previous versions were falling into 100%. In the 4.10 version it jumps over 100%...

[Luigi]

Zoom to orginal size

Earlier versions of IV showed the pics original size when zooming in/out. Now it jumps over that size Please bring back this function...for both clicking on the zoom tool and zooming with strg+mouse wheel!!

Thanks

[Bhikkhu Pesala]

Please search before posting.

[Luigi]

Please search before posting.

Thanks. I guess I was just using the wrong words for my search I'll try to enhance that

[piersg]

Me Too...

Joined the forum just to add to the comments about the new zoom functionality in 4.10 (this and other threads). I much preferred the old system, to the extent that I will be removing 4.10 and going back to 3.99 (luckily, I still have the installation files) after posting this message.

I like the idea of fixed zoom steps as an alternative.

[sandman]

Joined the forum just to add to the comments about the new zoom functionality in 4.10 (this and other threads). I much preferred the old system, to the extent that I will be removing 4.10 and going back to 3.99 (luckily, I still have the installation files) after posting this message.

I like the idea of fixed zoom steps as an alternative.

I've used IV for years, but I also went back to 3.99 for the same (and only!) reason. 4.10 has good features, including the paint plugin, but is not worth losing the old zoom ratios.

[ChuckE]

Except for Bhikkhu Pesala, who seems to be the only proponent of this new method, you'd think that if there are people who like this 'new' method, that they'd speak up. I just read through this entire thread and except for Bhikkhu Pesala, everyone else wants the return of the old method.

To counteract, or perhaps to appease, the change of the tool, I still stand by my suggestion that either method be selectable via a Preference selection. With the default being the 'old' method.

Even better, using the Ctrl or Shift keys to select one method over the other (another proposal by me) becomes another nice trick. But I would not hold my breath for that.

[Bhikkhu Pesala]

No, I don't like the new method, at least not as it is. It is well broken, but it could be fixed. What I like is the geometric progression of the zoom level instead of the arithmetic progression.

[Sam_Zen]

So the new method first has to be developed further.
Then at least there should be a choice in method, as ChuckE proposed.

[ChuckE]

A geometric progression? Are we going round and round? in circles?

[Sam_Zen]

You make me curious. How many dimensions are we talking about here ?

[Bhikkhu Pesala]

The algorithm could round to the nearest value from a predefined table to give more user-friendly values.

Zoom in and out would then use fixed values and would always return to 100% The zoom step would have a greater effect at the upper end of the range and a smaller effect at the lower end of the range. This means fewer keystrokes and finer control at the low end.

A factor of 35% provides a quick progression down to 5% zoom and up to 1,000% zoom. Users could change the zoom factor in preferences as they can now, but the default would be 35% instead of 10% The default would give a result like this:

4.90222789063 = 5
7.5418890625 = 8
11.60290625 = 12
17.850625 = 20
27.4625 = 30
42.25 = 50
65 = 75
100 = 100
135 = 150
182.25 = 200
246.0375 = 250
332.150625 = 350
448.40334375 = 450
605.344514063 = 600
817.215093984 = 800
1103.24037688 = 1100

The fixed value table would have presets at 1% steps up to 15%, 5% steps up to 50% 10% steps up to 100%, 25% steps up to 200%, 50% steps up to 500%, 100% steps up to 1,500% 500% steps up to 5,000, then 1,000% steps on to 5,000 % (maximum).

Choosing a higher zoom factor of 50 would give a result like this:

3.125 = 3
6.25 = 6
12.5 = 12
25 = 25
50 = 50
100 = 100
150 = 150
225 = 200
337.5 = 350
506.25 = 500
759.375 = 750
1139.0625 =1,100
1708.59375 = 1,700
2562.890625 =2,500

A finer step of 20% would give a result like this:

4.3980465111 = 4
5.49755813888 = 5
6.8719476736 =7
8.589934592 = 9
10.73741824 = 11
13.4217728 = 13
16.777216 = 15
20.97152 = 20
26.2144 = 25
32.768 = 30
40.96 = 40
51.2 =50
64 =60
80 = 80
100 = 100
120 =120
144 =150
172.8 =175
207.36 =200
248.832 = 250
298.5984 = 300
358.31808 =350
429.981696 =450

[Sam_Zen]

If this is a non-lineair approach to the zoom in/out procedure, I will agree.
In practice it will be that one first choose for a rough zoom-in, but approaching the desired result with next steps,
needs a less rough, more precision of dimension of each step zooming in.

[ChuckE]

The algorithm could round to the nearest value from a predefined table to give more user-friendly values.

Zoom in and out would then use fixed values and would always return to 100% The zoom step would have a greater effect at the upper end of the range and a smaller effect at the lower end of the range. This means fewer keystrokes and finer control at the low end.

A factor of 35% provides a quick progression down to 5% zoom and up to 1,000% zoom. ... ... ...
(the rest was deleted for fear of boring the reader even more).

Holy cow Bhikkhu! What the heck?! Who cares about all the math? Why complicate a simple thing like zooming in or out at 10% intervals? Are you worried about having to press the key bunches of times? why? Every keyboard already has an auto-repeat when you hold down the key. I just timed the current version (v4.10) and saw that (on my PC) it takes just 3 seconds to go from minimum zoom all the way up to max zoom. That was at a setting of 10% steps. When I adjusted the steps to 5%, then the time from minimum to max was just 7 seconds.

(By the way, in doing this I discovered another bug, but I'll enter that later.)

So then I went to an earlier version of IrfanView that did not have this "weird" zoom scheme, where the steps actually were 10% and saw that when going from min to max still just took 5 seconds, and using the step of 5% the min-max time was also just 10 seconds.

All the geometric, logarithmic, linear, isometric, barometric, bombastic or anything else calculations are not needed. Pure and simple 10% (or whatever value zoom steps the user wants) and if you need to get to the extremes, it is only a few seconds, in either direction, to get there.

I will be making one more suggestion now, though, that all this zoom zoom has shown me would be nice to have:
How about an immediate zoom level? If there was a simple way of entering in a particular zoom amount, like 123% that I can immediately get there. I see a lack of fineness in any of these schemes. If I press the keys a number of times, what if I get just a few percentage points more than I want? Going back a step is going to just pass up the desired value too! How about a "Z" key? where I could just type in the exact amount of zoom that I want? There could even be a type-in box on the footer (by clicking on the current zoom% indication, to type into. Thus, I could use the +&- keys to get most rough zooming done (usually sufficient) and if I need a finer step, a more exact value, I can press the "Z" key and enter it.

I'll make that suggestion in the Feature Request forum. Along with entering the bug, in the appropriate forum, that I found while zooming.