[pschlute]

I can understand 100% zoomed in on my display* , or 1 to 1 pixel on display, but 100% crop always got me confused.


*(100% preview on camera wasn't even clear to me until it was discussed in an recent thread)

100% "zoomed" on a computer monitor or camera LCD is the same thing...1 pixel in the image is displayed by one pixel on the viewing device. In any viewing/editing software you can select "view actual size", or view 100% or even double click. This is the same as using the cameras e-dials to zoom your image to 100%

Historically when someone wanted to post on a forum an image or part of an image that could be examined at 100% pixel level so that issues like focus or CA can be discussed, there was always problems:

1.Posting the full image would not be possible because most forums have a maximum size and would downsize the image.
2.Bandwidth issues would mean that it would be slow to display for most users.
3. Anyone viewing the full image at 100% could not be sure they were looking in the right place in the image in question.

So the poster would make a crop of the original image without any re-sizing and post that.

100% means that the posted image can be viewed at 1:1 on most folks screens **. Crop means it is a portion of the original image. The 100% does not refer to the crop itself.

** As long as the pixel dimensions of the crop is chosen suitably. A 100% crop with a pixel height of 2000 would be no good in this regard as it is taller than most folks screen resolutions and would be downsized by the forum software anyway.

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Last edited by pschlute; 11-07-2021 at 06:35 AM.

[biz-engineer]

Exactly, that's why 100% "crop" on an HD display is not the same as 100% "crop" on an 4K display. What appear sharp on 4K may not be on HD.

[BigMackCam]

Exactly, that's why 100% "crop" on an HD display is not the same as 100% "crop" on an 4K display. What appear sharp on 4K may not be on HD.

But 100% simply refers to 1:1 reproduction - i.e. one pixel in the image is displayed by one pixel on the display. The fact that its physical dimensions differ by the size of display and its pixels isn't relevant. "100% crop" has nothing to do with the relative utility between display types - it merely refers to a cropped image that's displayed at 1:1 reproduction.

[pschlute]

Exactly, that's why 100% "crop" on an HD display is not the same as 100% "crop" on an 4K display.

It is in pixel size

What appear sharp on 4K may not be on HD

Because the 4k monitor is a smaller physical image than the HD one. This would simply show that the 4k monitor is hiding the defects of the image.

i look at images posted online across numerous sites on my iphone; my ipad; and my computer monitor. I understand they are all different physical sizes. I think anyone posting images and viewing images will do too.

[BigMackCam]

IBecause the 4k monitor is a smaller physical image than the HD one. This would simply show that the 4k monitor is hiding the defects of the image.

Not wanting to de-rail the thread, but... as an interesting aside on this subject:

HD, being the prevalent display resolution for so long, is now the lowest common denominator and what we should probably assume for the target when creating 1:1 or "100%" crops for consumption by others in these and other forums. Viewers with 4K displays may need to (and probably already do) use browser and/or display scaling to see online images at useful physical dimensions.

In raw development tools, it's probably necessary to view images at 2:1 (200%) or even greater reproduction ratio on 4K displays in order to examine and work at pixel-level detail, unless the user has a BIG monitor. It's great to view full-size high-resolution images and video on a 4K monitor for enjoyment and entertainment, but when assessing lens and sensor performance in a photo, you really want to be able to see each pixel in the image. HD, for all its limitations on a larger laptop or regular desktop display, is pretty much ideal for that.

For a short while I owned and used an HP laptop with 15.6" 4K display. When editing photos and viewing others' images, I ended up scaling the display to HD resolution. In fact, I only really utilised 4K for video streaming...

[pschlute]

In raw development tools, it's probably necessary to view images at 2:1 (200%) or even greater reproduction ratio on 4K displays

I am no expert, but once you start looking at an image at 200% , you are surely relying on your computer graphics interpolation of the image and no longer looking at what the sensor recorded ?

[stevebrot]

Exactly, that's why 100% "crop" on an HD display is not the same as 100% "crop" on an 4K display. What appear sharp on 4K may not be on HD.

That is why it is usually inappropriate to use 4K for photo editing or quality evaluation and to use tools that provide lower resolution within the 4K envelope. 1080 is the highest resolution I run on my editing monitor.


Steve

[BigMackCam]

I am no expert, but once you start looking at an image at 200% , you are surely relying on your computer graphics interpolation of the image and no longer looking at what the sensor recorded ?

Indeed, but on a 4K monitor - unless it's a BIG monitor - scaling beyond 100% reproduction is the only way to see individual pixels in an image. That's the "gotcha" of a 4K display for us photographers... it's wonderful for viewing our photos at high pixel density as they would be in print, since we don't see individual pixels - but not so great for assessing lens & sensor performance or editing photos, IMHO.

My current laptop has a 17" HD display, and my 24" BenQ desktop monitor is QHD. Both have relatively similar pixel densities for the same physical area. At normal working distance to the screen, I find them ideal for photo editing, but to view a photo to its best effect, I sit or step back from the screen a little...

[biz-engineer]

But 100% simply refers to 1:1 reproduction - i.e. one pixel in the image is displayed by one pixel on the display. The fact that its physical dimensions differ by the size of display and its pixels isn't relevant. "100% crop" has nothing to do with the relative utility between display types - it merely refers to a cropped image that's displayed at 1:1 reproduction.

If I display a 2Mpixels image on my 4K display, it is displayed at 100% but not cropped. Why call it a crop then?

[Fogel70]

I am no expert, but once you start looking at an image at 200% , you are surely relying on your computer graphics interpolation of the image and no longer looking at what the sensor recorded ?

I do not think there will be any interpolation when viewing images at 200%. At least not in photo editing softwares, in editing mode.
Then each captured pixel will be displayed on 4 pixels on screen.

On a 4k display at 200% you will see the image at same magnification on screen as at 100% on a 1080p screen of same size.
Where you see each captured pixel on 1 pixels on the 1080p screen and on 2x2 pixels on the 4k screen.

[BigMackCam]

If I display a 2Mpixels image on my 4K display, it is displayed at 100% but not cropped. Why call it a crop then?

If that 2MP image is what came out of the camera originally, it's not a crop. If, however, it started as a 24MP image that has had the top, bottom or sides cropped away to leave an isolated 2MP portion of the original, then it's a crop.

In the context of these forums, a "100% crop" is an isolated portion of a full-resolution image where that portion has pixel dimensions smaller than both the target display and the forum software's maximum image size. The intention of a "100% crop" is that it can be displayed in its entirety at 1:1 reproduction ratio - i.e. one pixel in the cropped image is represented by one pixel on the display - on the range of devices used by forum members, for the purpose of assessing rendering details.

[MarkJerling]

Not wanting to de-rail the thread, but... as an interesting aside on this subject:

HD, being the prevalent display resolution for so long, is now the lowest common denominator and what we should probably assume for the target when creating 1:1 or "100%" crops for consumption by others in these and other forums. Viewers with 4K displays may need to (and probably already do) use browser and/or display scaling to see online images at useful physical dimensions.

In raw development tools, it's probably necessary to view images at 2:1 (200%) or even greater reproduction ratio on 4K displays in order to examine and work at pixel-level detail, unless the user has a BIG monitor. It's great to view full-size high-resolution images and video on a 4K monitor for enjoyment and entertainment, but when assessing lens and sensor performance in a photo, you really want to be able to see each pixel in the image. HD, for all its limitations on a larger laptop or regular desktop display, is pretty much ideal for that.

For a short while I owned and used an HP laptop with 15.6" 4K display. When editing photos and viewing others' images, I ended up scaling the display to HD resolution. In fact, I only really utilised 4K for video streaming...

Funny, I noticed this for the first time tonight as I've been editing photos from our local marathon which i took on Sunday. I really cannot see pixels on the 4K display and at "100%" or "full size" view, the images look very different to what I was used to with my previous laptop!

[BigMackCam]

Funny, I noticed this for the first time tonight as I've been editing photos from our local marathon which i took on Sunday. I really cannot see pixels on the 4K display and at "100%" or "full size" view, the images look very different to what I was used to with my previous laptop!

Yup. On your display, I'd recommend editing at 200% / 2:1 reproduction.

When I had that HP ZBook G5 with 15.6" 4K DreamColor display, I only really used 4K for video streaming (and I'll admit it looked fantastic for that). For editing photos and appraising others' photos online, I switched the resolution to HD. I also found there were a few apps that weren't yet 4K friendly in terms of scaling, so switching to HD res was the solution for those too. As such, most of the time I just left the display resolution at HD

On my current Lenovo, the 17" HD display really isn't great for rendering small fonts in Windows 10. Even with ClearType enabled and adjusted, the fonts look pretty bad, with a lot of artefacts... so for general computing, it's less than ideal; but, it's great for photo editing, and "good enough" for video streaming...

I guess I was not the only one confused by this =D

And that that same non-native English speaker thinks that 100% crop means that all of the picture is there and not just a part? And that in that vein a 50% crop is a failed image you have taken, because only half of it is usable?
...
That we talk about the crop factor of a sensor and that in that case the word crop has a completely different meaning from the crop in 100% crop?
...
You do not disappoint, but I notice that all the explaining here makes 100% crop more obscure than it already was. I am under the impression that it is extremely difficult to give an answer to the OP's question. Luckily in my native language it is simple and clear to explain. I know what you do in the dark room and what the technique used is.

I'm still convinced the phrase is nonsense. In English, if you take one hundred per-cent of something away, it's all gone. To my mind, since I speak English and managed to learn a good bit about it despite having gone to public school, and if say I've done a thirty per-cent crop, then I've taken away a third of the picture or so. I've cropped it my thirty per-cent.
It's as if the jargon were designed to exclude the uninitiated by making things unnecessarily obtuse, obscure, and obfuscated.