G9 - Hi-res vs normal resolution – Bank note

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gardenersassistant Veteran Member • Posts: 5,589
G9 - Hi-res vs normal resolution – Bank note
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I have been following the ongoing discussions about high resolution images with great interest (for example here and here). I am quite interested in close-ups and decided to do a comparison of high resolution vs normal resolution with an unsophisticated setup I use to compare close-up and macro lenses by photographing a UK ten pound note at various magnifications. I have found this a useful subject because the bank note has a surprising amount of fine detail.

As discussed in the ongoing threads there are numerous issues about how to process images so as to make a meaningful comparison, for example in relation to sharpening. I will write down what I have done and show some comparisons, but everyone will have their own views as to how best to process and compare the images, so the raw files are in this Dropbox folder for anyone who wants to work on them and draw their own conclusions.

I captured a number of images, including some repetition to avoid picking any outliers for the comparisons. Only six of them are used for this post. There are three pairs of images, one pair at around 1:4 magnification, one pair at around 1:2 magnification and one pair at 1:1 magnification. Each pair comprises a high resolution image and a normal resolution image. Both images in each pair are from the same capture, thus sidestepping any issues about differences in shooting conditions or settings for the two images in each pair. Such issues do of course arise as between the three pairs, although I tried to keep the captures consistent, for example using focus peaking to try to ensure the camera was square on to the subject.

I used a G9 and an Olympus 60mm macro, with the camera on the “test rig” as illustrated above. I used an 8 second delay for the captures.

I use DXO PhotoLab as the first step in my close-up processing and so I used that for this exercise. Rather than use one of my own presets (I don’t have one for hi-res) I used the DXO Standard preset. I exported as DNG to Lightroom.

I used Auto Tone Control on the DNG files in Lightroom. Following on from the discussion in one of the linked threads I decided to sharpen each image individually with as much sharpening as I could without introducing artefacts. Obviously there is a judgement call here, which is one reason why others may prefer to work on the files for themselves, with their own favourite software and workflow, and to their own visual preferences. (This sharpening was in addition to the sharpening that PhotoLab had done.)

I tried a lot of combinations of Amount, Radius and Masking (I left Detail at 25 in all cases.)

Here are three examples of the normal resolution 1:4 magnification image. They are shown to the right of the centre of the image at 100% - I found the face particularly useful for looking for artefacts. The sharpening for these was as follows:

Left: no Lightroom sharpening.
Middle: Amount 29, Radius 2.4, Detail 25, Masking 90.
Right: Amount 40, Radius 1.4, Detail 25, Masking 90.

The one on the right definitely looked oversharpened to me. I wasn’t quite sure about the one in the middle but it didn’t look right to me. When I looked at 200% I saw artefacts.

I eventually decided to use no Lightroom sharpening at all for this one.

In contrast, the paired hi-res version seemed to take a fair bit of sharpening without producing artefacts. After trying various options I settled on Amount 46, Radius 0.9, Detail 25, Masking 83.

I exported the pair full size to JPEG 100% from Lightroom, using Screen Standard output sharpening. I was then ready to compare the hi-res and normal-res versions of the magnification 1:4 pair.

The next question of course is how to do the comparison: both at 100%, downsize the hi-res, upsize the normal-res, or somewhere in the middle, downsizing the hi-res and upsizing the normal-res? I tried all of these. But of course there are other options, for example comparing the full size normal-res version with a hi-res version exported from Lightroom with the normal-res pixel dimensions, so that Lightroom’s output sharpening would be appropriate for that size. This might be better than depending on viewer software to do the resizing to make the versions directly comparable size-wise. Or the comparisons could be done in Lightroom.

I used Faststone Image Viewer to compare the full size JPEG versions, resized by Faststone as appropriate. Because others may want to use a different comparison method, and/or may not want to depend on the parts of the images I have chosen to display, the full size JPEGs exported from Lightroom are included in the linked Dropbox folder.

With the hi-res version on the left and the normal-res version on the right, here are some comparisons of the 1:4 magnification pair.

Comparison 1 - Both at 100%

Comparison 2 - Hi-res downsized to match Normal-res

Comparison 3 - Normal-res upsized to match hi-res

Comparison 4 - Hi-res downsized, Normal-res upsized

Looking at Comparison 4 it seems to me that the hi-res version has better clarity than the normal-res version, has purer (not sure that is the right word, but anyway, better) colours (I’m looking for example at the yellow/gold wavy and meshed lines against the white background), has better microcontrast, has better “dimensionality” (the white dots in the mid regions look raised rather than simply looking to be a different colour on a flat surface) and makes visible additional small-scale detail.

For another comparison, I wondered how the hi-res magnification 1:4 version would compare to a 1:2 magnification normal-res version.

Similar issues arose with the sharpening and after more experimenting, for the 1:2 magnification normal-res version I used Amount 7, Radius 1.4, Detail 25, Masking 93. (There is a version with Amount 40 and the same other parameters in the Dropbox folder. I was uncomfortable with the look of it.)

This comparison has the hi-res magnification 1:4 version on the left and the normal-res 1:2 version on the right. Both are at 100%

It seems to me that the normal-res version has better microcontrast, dimensionality and fine detail. The reds are darker in the normal-res version. I don’t know if that is good or bad, but I find it confuses my eyes when trying to decide about clarity, about which I am undecided.

Finally, the hi-res 1:4 version versus a 1:1 magnification normal-res version.

For the 1:1 magnification version I used sharpening Amount 39, Radius 1.4. Detail 25, Masking 93.

Here is the hi-res magnification 1:4 version upsized on the left and the normal-res 1:1 version downsized on the right.

The normal-res version looks better to me in all five of the aspects mentioned above.

That is as far as I have got at the moment. Following on from this (somewhat) controlled but essentially contrived exercise I used hi-res for a couple of real-world close-up scenes out in the garden today but I haven’t looked at them yet.

Panasonic Lumix DC-G9
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