Picture size for posting

Scrolling bars are generated by pictures larger than their boxes. It's a coding issue, except if it's intentional.

Those boxes are properly managed in Dyxum since inserting a picture larger than 1024px will not make the picture bigger. The original file will be resized to the box, allowing high-res screen to display a hi-res photo.

On some forums the picture size is checked, and refused if larger than 1024px.

Hi all, interesting discussion, I will not repeat its evolution and what led me to question the utility of Dyxum's upload recommendations here. They are available in Is the World ready for 4k.

My comments are:

1) I fully support limited upload resolutions for all the reasons listed. FWIW I am one of those relics with DSL as internet service. Big photo files are a pain for me.

2) My question was why Dyxum specifies an upload size that does not correspond to either display standards or sensors. If it was simply convenient numbers that yield an upload file size of a little less than 1Mb it accomplishes that goal. Subsequent screen display adapter remapping for photo pixels to display on a screen with a different pixel ratio will have an impact on displayed sharpness.

3) All HD formats are ratios of 16:9. Pixel counts vary by HD standard, but all have a ratio of 16:9 width to height as a common denominator. They will map relatively cleanly between standards. HD was standardized in 1993, coming up on 25 years ago. The 7D was not yet even a gleam in a Minolta engineers eye. HD standards have not just fallen off the turnip wagon.

4) There are two HD standards that yield files around 1mb. They are HD Ready (720p) at 1280x720 and HD Basic at 1366x768. HD Ready produces files that are slightly smaller than the Dyxum maximum file size recommendation and scale directly to 4k resolution HD standards.

5) Question, What size does Dyxum resize to? The upload standard is recommended at 1025x960 max, but an example states that a display at 600x900 (sic) will wash out sharpening done at a higher resolution. Sharpening will also be lost on a photo sharpened at a pixel ratio that varies from that of the display.

6) There is nothing that prevents us from formatting photos for uploading at HD ready, or another HD standard. HD Ready width exceeds the Dyxum recommendation, but the height is lower. It produces a file size that is smaller than the Dyxum max recommendation. However, that gets me back to the question I asked in (5) above about Dyxum resizing. If we format to any size that varies from Dyxum's resizing (the 600x900 example seems very unlikely, even though it is a subset of 3:2 sensor ratio in portrait mode) nothing matters, the result is just varying degrees of fuzzy.

7) I respectfully suggest that the Lords of Dyxum Towers consider a minor adjustment of the picture format to an HD standard, HD Ready (720p) would work. That would also reduce upload file sizes moderately from the current recommendation while preserving sharpening.

I don't understand a need for a change from the current size limit based on concerns about either sensor dimensions or HD standards affecting sharpness.

If you resize a photo, resize it to be less than 1024 horizontally and less than 960 vertically. If you're picky about the resized dimensions, try some variations. Example: 6000x4000 can be proportionally resized to 1020x680, 1000x667, 960x640, etc. Then sharpen the resized version before posting according to output sharpening recommendations, which is standard practice anyway.

I suppose those with a keen interest in this can do exactly that and show the various results, either here or in a dedicated thread. Then we can all weigh in on whether or not sharpness or anything else has been compromised.

Cliff wrote: The easiest solution is to edit and upload pictures at the resolution Dyxum resizes to. That would be easier for Dyxum too. While 1024x960 is specified as the max, there is no indication of what Dyxum resizes to, although there is an implication it might be 600x900. There is also logic to Dyxum resizing to an industry standard like HD.

Just tested, Dyxum resizes to max 1028 horizontal or max 1000 vertical, whichever is limiting first. The other dimension is then below the other maximum. Hope this makes sense

Edited by pegelli - 13 December 2017 at 18:35

pegelli wrote: Just tested, Dyxum resizes to max 1028 horizontal or max 1000 vertical, whichever is limiting first. The other dimension is then below the other maximum. Hope this makes sense

Firefox says this image from Brandy was originally 960px × 959px but was scaled to 901px × 900px. Internet Explorer says 901 x 900 pixels. Is it my browsers or is Dyxum resizing limiting the vertical dimension to 900?

Edited by clk230 - 09 January 2018 at 07:52

OK, so if I make Firefox or Internet Explorer full screen (F11) then it shows full size. My monitor's native resolution is 1920x1080 so perhaps both browsers resize so that whole vertical scope of the image is visible even with the window menu bar and status bus etc.

Nice discussion :)
To solve the mystery once and for all: Dyxum does not rescale images Dyxum kindly asks browsers to do this operation by setting appropriate CSS properties for the image. Strictly speaking the CSS is following:

.msgBody img, .PMmsgBody img {     max-width: 1024px;     height: auto;     max-height: 900px;     margin: 0px;     padding: 0px; }

So, the image should be rescaled to 1024 pixels if it is wider and 900 pixels if it is taller. Exact interpretation is up to the browser. One can play with CSS in-browser (look for appropriate plugins/extensions) and override these settings.