Exporting Pictures for Web Site

I use Lightroom and would like to know perferred export settings that help maintain quality of image and keep a low file size. I have seen photography sites that have small file size, below 100 kb with good quality. I have even seen photography templates that have images with low file size with no image quality. Mine are usually between 300kb-600kb. Just want to avoid downloading time when someone is viewing my site.

Thank you in advanced.

1024x768 pixels = roughly just under 1mp, slightly larger than the images you download from FB. That should be good enough for most web uses.

For forums I resize to 1024 on the long side. I just tried it at quality settings of 100 and 80 checked plus set the keep to box to under 100 K.

100 was about 650. 80 was about 350. Not much difference between 80 and 100 but I made crop using a squirrel shot and look at the fur under a magnifying glass. I'm pretty sure I seen a tad more pixilation along single hair edges. I had read somewhere that going over 80 for screen did not gain anything but I can't say for sure.

You could clearly see major IQ drop at 100.

For facebook or emails I typically resize to about 800 on the long side.

I come from a graphic design background. For me getting good quality images/files means high file sizes as they are used for printing. Depending on dimension of file of course. I use photoshop for business cards, flyers of that category so they are always a fixed size. I don't make images for facebook and rarely use emails to send pictures.

When I use Lightroom. I keep resolution at 72 but have gone on quality between 80-85. I have used at times up to 100 but I have not seen much difference, other that it creates a bigger size.When I use similar settings to export photographs and use them for my site I can notice delays fpr viewing a bit. Not a big deal but people nowadays don't have the patience to wait a few more seconds. Just trying to make it easier for viewing my gallery faster. Perhaps just have to shrink picture dimension a bit then or when making a new site to not show at full screen.

Resolution has nothing to do with screen viewing. That only applies to printing. You can set it anywhere and it won't make a difference.

Why am I uploading 1024? Was that a max size here at one time? I know I can go bigger but no need to eat up server space and it is easier to view.

If not due to a previous max why 1024 specifically? Are there downsampling ratios best suited as related to sensor size and/or megapixels? I was going to start another thread on this but I'll try here.

Yes I agree, only applies to printing.

So is there really a way to shrink down file size without compromising on the image quality for viewing on websites?

digital paradise wrote in post #18544495
Resolution has nothing to do with screen viewing. That only applies to printing. You can set it anywhere and it won't make a difference.

You do notice if you set your image to 18 dpi. Though the file size is very small.

Which one set to a resolution of 1 and which one is 1000?

HOSTED PHOTO
please log in to view hosted photos in full size.

HOSTED PHOTO
please log in to view hosted photos in full size.

I think the 1024 was the largest size on the old forum software. Pekka can verify if that is so or not, but I seem to remember when he wrote AMASS that it went up to 1280.

That size is due to the highest resolution an average user is likely to use. When 4K becomes pretty much standard, that limit will likely increase. Of course even then it may be wise to stay under that for bandwidth purposes.

Yeah it went to 1280. I noticed I get more fine jaggies with my 5D4 than I did with 5D3 and my 7D2. I never really thought about it until now.

When creating JPEG files from Adobe software they have two interface scales for the quality setting, 0 to 12 and 0 to 100. In both of these scales there are only thirteen different levels of compression applied. Using the 0 to 12 scale is easy, since each value is actually a difference in actual compression. For the 0 to 100 scale you need to divide 101 by 13 to get the step value, which is 7.76. If you then divide the scale value by the step value, and use the number in front of the decimal point you will get the correct conversion to the 0 to 12 scale. So Q80 and Q85 both give the same level 10 compression.

I have run extensive comparisons of images exported at all 13 levels of JPEG compression, to an 8 bit TIFF. All the images were exported from Lr with the only differences being the level of compression for each of the 13 JPEG files, and of course the change to TIFF for the master image. All of the files were loaded to one psd file as layers, and the blend modes were all set to difference. This allows one to see the actual difference between each colour channel in every pixel. When dealing with the higher quality images the image pretty much looks black, so in order to make the differences more notable I had to add a levels layer too, so that pixel values from 0 to 8 were spread over the whole 0-255 range.

What soom becomes obvious is that when working at level 10 (78 - 85), and above, the differences between the various JPEG levels and the uncompressed TIFF file are all of the same magnitude. Oddly the difference between level 10 and 12 for the JPEG files was greater than the difference from the uncompressed JPEG.

It is important to know that images saved in the JPEG format are not stored as RGB triplets, as they are in a TIFF file, or when working with them in an image editor. Instead they are converted to a monochromatic brightness channel, plus to chromiance channels for the colour. The pixels are subdivided into 8×8 blocks, this then has some clever maths applied to it, a Discrete Cosine Transform, which can is a format that can allow you to remove some data, without unduly affecting the perceived image quality. Even if you don't do the compression stage though, you do get some very small measurable, but invisible, artifacts introduced.

Essentially, compared to an image that hasn't been converted to JPEG, there is no real measurable difference in image quality between Levels 10 and 12. There is however a very large difference in file size on disk. Compared to the original uncompressed data a Level 10 JPEG file is between 40% and 60% smaller. Since a maximum quality JPEG file is going to be the same size on disk as an 8 bit TIFF, and it is possible to reduce the size by using lossless LZW compression, I would pick that option over the JPEG. If JPEG is required I see absolutely no need to ever use higher than Level 10 quality.

Finally when posting images online I now post at a maximum of 1280 px long edge, Level 10 JPEG and sRGB. They give a good size on screen, but at least you can't get a good large sized print from one.

Alan