Gallery images blurry on mobile

When I look at gallery images on my iPhone XR or 2017 iPad the thumbnails look fine, but expand the images and they appear blurry. The more images that are in the gallery (And the smaller the thumbnail) the worse the loss in quality is.

This is especially the case on my phone in portrait mode, if I rotate the landscape mode and open it again the image generated by ghost appears to be higher resolution. They always look fine on PC, even when I use “Responsive Mode” on FireFox to test. But that could just be because my PC Monitor is a lower DPI than the Retina Display on my iPhone. Images are noticeably blurry on iPad as well to be clear, but on iPhone it’s worse.

Here you can see how the image appears on my phone from a screenshot I took. to the right is the same image when I try to download it through my phone. The right side is also how it appears on PC. If I put my phone in landscape orientation and reload the image will appear less blurry but still not ideally sharp.

I tried disabling image optimization in the config file, restarting Ghost/Ubuntu and re-uploading the images but it doesn’t seem to solve the problem. I would prefer to leave image optimization on for the increase in page load speed it provides anyway. It looks like what’s happening is when you expand the image on iOS it never loaded a larger version of the file and just enlarges the thumbnail, hence the quality loss (Especially on larger galleries).

Is there a way to tweak the code for how Ghost optimizes images either specifically for iOS devices or even just overall to increase the resolution it shoots out on mobile?

Here is the site in question where I’m having the issue:


Ghost Version: 2.29.1

Thanks for highlighting this @VickyTheDemon. I’ve created an issue on GitHub where you can track the progress of the issue:

Edit: Quick question @VickyTheDemon, which theme are you using for your site? Is it a custom one?

I read the comments on GitHub. I am using a 3rd Party Theme yes, one called Polar (Found here). I switched the site back to Casper momentarily to test the default theme and Casper doesn’t appear to even support the functionality of zooming in on Gallery Images.

But that certainly isn’t a feature I want to give up. I’ll have to see if I can contact the theme designer then or come up with a solution myself.

@VickyTheDemon can you share one of your URLs which exhibits the problem? That would be the best way for anyone on here to help you as it would let us see the code and what’s going wrong

Hi @Kevin, you can see an example of the problem I described at the link I provided in my original post. Here is that link again for your convenience:

Example Gallery With Issue

I’m looking through the JS code my theme uses, and it appears to use the following open source plugin to accomplish the zoom in on gallery images when touched/clicked on.

Medium Zoom on GitHub

Here is the actual code, straight from the theme.

/*====================================================
4. medium zoom
====================================================*/
/*! medium-zoom 1.0.1 | MIT License | https://github.com/francoischalifour/medium-zoom */
!function(e,t){"object"==typeof exports&&"undefined"!=typeof module?module.exports=t():"function"==typeof define&&define.amd?define(t):e.mediumZoom=t()}(this,function(){"use strict";var H=Object.assign||function(e){for(var t=1;t<arguments.length;t++){var o=arguments[t];for(var n in o)Object.prototype.hasOwnProperty.call(o,n)&&(e[n]=o[n])}return e},o=function(e){return"IMG"===e.tagName},C=function(e){return e&&1===e.nodeType},O=function(e){return".svg"===(e.currentSrc||e.src).substr(-4).toLowerCase()},l=function(e){try{return Array.isArray(e)?e.filter(o):(t=e,NodeList.prototype.isPrototypeOf(t)?[].slice.call(e).filter(o):C(e)?[e].filter(o):"string"==typeof e?[].slice.call(document.querySelectorAll(e)).filter(o):[])}catch(e){throw new TypeError("The provided selector is invalid.\nExpects a CSS selector, a Node element, a NodeList or an array.\nSee: https://github.com/francoischalifour/medium-zoom")}var t},x=function(e,t){var o=H({bubbles:!1,cancelable:!1,detail:void 0},t);if("function"==typeof window.CustomEvent)return new CustomEvent(e,o);var n=document.createEvent("CustomEvent");return n.initCustomEvent(e,o.bubbles,o.cancelable,o.detail),n},c=window.Promise||function(e){function t(){}e(t,t)};return function(e,t){void 0===t&&(t={});var o=t.insertAt;if(e&&"undefined"!=typeof document){var n=document.head||document.getElementsByTagName("head")[0],i=document.createElement("style");i.type="text/css","top"===o&&n.firstChild?n.insertBefore(i,n.firstChild):n.appendChild(i),i.styleSheet?i.styleSheet.cssText=e:i.appendChild(document.createTextNode(e))}}(".medium-zoom-overlay{bottom:0;left:0;opacity:0;position:fixed;right:0;top:0;transition:opacity .3s;will-change:opacity}.medium-zoom--opened .medium-zoom-overlay{cursor:pointer;cursor:zoom-out;opacity:1}.medium-zoom-image{cursor:pointer;cursor:zoom-in;transition:transform .3s cubic-bezier(.2,0,.2,1)}.medium-zoom-image--hidden{visibility:hidden}.medium-zoom-image--opened{cursor:pointer;cursor:zoom-out;position:relative;will-change:transform}"),function t(e){var o=1<arguments.length&&void 0!==arguments[1]?arguments[1]:{},n=function(){for(var e=arguments.length,t=Array(e),o=0;o<e;o++)t[o]=arguments[o];var i=t.reduce(function(e,t){return[].concat(e,l(t))},[]);return i.filter(function(e){return-1===v.indexOf(e)}).forEach(function(e){v.push(e),e.classList.add("medium-zoom-image")}),d.forEach(function(e){var t=e.type,o=e.listener,n=e.options;i.forEach(function(e){e.addEventListener(t,o,n)})}),L},i=function(){var p=(0<arguments.length&&void 0!==arguments[0]?arguments[0]:{}).target,g=function(){var e={width:window.innerWidth,height:window.innerHeight,left:0,top:0,right:0,bottom:0},t=void 0,o=void 0;if(b.container)if(b.container instanceof Object)t=(e=H({},e,b.container)).width-e.left-e.right-2*b.margin,o=e.height-e.top-e.bottom-2*b.margin;else{var n=(C(b.container)?b.container:document.querySelector(b.container)).getBoundingClientRect(),i=n.width,r=n.height,d=n.left,a=n.top;e=H({},e,{width:i,height:r,left:d,top:a})}t=t||e.width-2*b.margin,o=o||e.height-2*b.margin;var m=E.zoomedHd||E.original,l=O(m)?t:m.naturalWidth||t,c=O(m)?o:m.naturalHeight||o,u=m.getBoundingClientRect(),s=u.top,f=u.left,p=u.width,g=u.height,h=Math.min(l,t)/p,v=Math.min(c,o)/g,z=Math.min(h,v),y="scale("+z+") translate3d("+((t-p)/2-f+b.margin+e.left)/z+"px, "+((o-g)/2-s+b.margin+e.top)/z+"px, 0)";E.zoomed.style.transform=y,E.zoomedHd&&(E.zoomedHd.style.transform=y)};return new c(function(t){if(p&&-1===v.indexOf(p))t(L);else if(E.zoomed)t(L);else{if(p)E.original=p;else{if(!(0<v.length))return void t(L);var e=v;E.original=e[0]}var o,n,i,r,d,a,m,l,c;if(E.original.dispatchEvent(x("medium-zoom:open",{detail:{zoom:L}})),y=window.pageYOffset||document.documentElement.scrollTop||document.body.scrollTop||0,z=!0,E.zoomed=(o=E.original,n=o.getBoundingClientRect(),i=n.top,r=n.left,d=n.width,a=n.height,m=o.cloneNode(),l=window.pageYOffset||document.documentElement.scrollTop||document.body.scrollTop||0,c=window.pageXOffset||document.documentElement.scrollLeft||document.body.scrollLeft||0,m.removeAttribute("id"),m.style.position="absolute",m.style.top=i+l+"px",m.style.left=r+c+"px",m.style.width=d+"px",m.style.height=a+"px",m.style.transform="",m),document.body.appendChild(w),b.template){var u=C(b.template)?b.template:document.querySelector(b.template);E.template=document.createElement("div"),E.template.appendChild(u.content.cloneNode(!0)),document.body.appendChild(E.template)}if(document.body.appendChild(E.zoomed),window.requestAnimationFrame(function(){document.body.classList.add("medium-zoom--opened")}),E.original.classList.add("medium-zoom-image--hidden"),E.zoomed.classList.add("medium-zoom-image--opened"),E.zoomed.addEventListener("click",h),E.zoomed.addEventListener("transitionend",function e(){z=!1,E.zoomed.removeEventListener("transitionend",e),E.original.dispatchEvent(x("medium-zoom:opened",{detail:{zoom:L}})),t(L)}),E.original.getAttribute("data-zoom-src")){E.zoomedHd=E.zoomed.cloneNode(),E.zoomedHd.removeAttribute("srcset"),E.zoomedHd.removeAttribute("sizes"),E.zoomedHd.src=E.zoomed.getAttribute("data-zoom-src"),E.zoomedHd.onerror=function(){clearInterval(s),console.warn("Unable to reach the zoom image target "+E.zoomedHd.src),E.zoomedHd=null,g()};var s=setInterval(function(){E.zoomedHd.complete&&(clearInterval(s),E.zoomedHd.classList.add("medium-zoom-image--opened"),E.zoomedHd.addEventListener("click",h),document.body.appendChild(E.zoomedHd),g())},10)}else if(E.original.hasAttribute("srcset")){E.zoomedHd=E.zoomed.cloneNode(),E.zoomedHd.removeAttribute("sizes");var f=E.zoomedHd.addEventListener("load",function(){E.zoomedHd.removeEventListener("load",f),E.zoomedHd.classList.add("medium-zoom-image--opened"),E.zoomedHd.addEventListener("click",h),document.body.appendChild(E.zoomedHd),g()})}else g()}})},h=function(){return new c(function(t){!z&&E.original?(z=!0,document.body.classList.remove("medium-zoom--opened"),E.zoomed.style.transform="",E.zoomedHd&&(E.zoomedHd.style.transform=""),E.template&&(E.template.style.transition="opacity 150ms",E.template.style.opacity=0),E.original.dispatchEvent(x("medium-zoom:close",{detail:{zoom:L}})),E.zoomed.addEventListener("transitionend",function e(){E.original.classList.remove("medium-zoom-image--hidden"),document.body.removeChild(E.zoomed),E.zoomedHd&&document.body.removeChild(E.zoomedHd),document.body.removeChild(w),E.zoomed.classList.remove("medium-zoom-image--opened"),E.template&&document.body.removeChild(E.template),z=!1,E.zoomed.removeEventListener("transitionend",e),E.original.dispatchEvent(x("medium-zoom:closed",{detail:{zoom:L}})),E.original=null,E.zoomed=null,E.zoomedHd=null,E.template=null,t(L)})):t(L)})},r=function(){var e=(0<arguments.length&&void 0!==arguments[0]?arguments[0]:{}).target;return E.original?h():i({target:e})},v=[],d=[],z=!1,y=0,b=o,E={original:null,zoomed:null,zoomedHd:null,template:null};"[object Object]"===Object.prototype.toString.call(e)?b=e:(e||"string"==typeof e)&&n(e),b=H({margin:0,background:"#fff",scrollOffset:40,container:null,template:null},b);var a,m,w=(a=b.background,(m=document.createElement("div")).classList.add("medium-zoom-overlay"),m.style.background=a,m);document.addEventListener("click",function(e){var t=e.target;t!==w?-1!==v.indexOf(t)&&r({target:t}):h()}),document.addEventListener("keyup",function(e){27===(e.keyCode||e.which)&&h()}),document.addEventListener("scroll",function(){if(!z&&E.original){var e=window.pageYOffset||document.documentElement.scrollTop||document.body.scrollTop||0;Math.abs(y-e)>b.scrollOffset&&setTimeout(h,150)}}),window.addEventListener("resize",h);var L={open:i,close:h,toggle:r,update:function(){var e=0<arguments.length&&void 0!==arguments[0]?arguments[0]:{},t=e;if(e.background&&(w.style.background=e.background),e.container&&e.container instanceof Object&&(t.container=H({},b.container,e.container)),e.template){var o=C(e.template)?e.template:document.querySelector(e.template);t.template=o}return b=H({},b,t),v.forEach(function(e){e.dispatchEvent(x("medium-zoom:update",{detail:{zoom:L}}))}),L},clone:function(){var e=0<arguments.length&&void 0!==arguments[0]?arguments[0]:{};return t(H({},b,e))},attach:n,detach:function(){for(var e=arguments.length,t=Array(e),o=0;o<e;o++)t[o]=arguments[o];E.zoomed&&h();var n=0<t.length?t.reduce(function(e,t){return[].concat(e,l(t))},[]):v;return n.forEach(function(e){e.classList.remove("medium-zoom-image"),e.dispatchEvent(x("medium-zoom:detach",{detail:{zoom:L}}))}),v=v.filter(function(e){return-1===n.indexOf(e)}),L},on:function(t,o){var n=2<arguments.length&&void 0!==arguments[2]?arguments[2]:{};return v.forEach(function(e){e.addEventListener("medium-zoom:"+t,o,n)}),d.push({type:"medium-zoom:"+t,listener:o,options:n}),L},off:function(t,o){var n=2<arguments.length&&void 0!==arguments[2]?arguments[2]:{};return v.forEach(function(e){e.removeEventListener("medium-zoom:"+t,o,n)}),d=d.filter(function(e){return!(e.type==="medium-zoom:"+t&&e.listener.toString()===o.toString())}),L},getOptions:function(){return b},getImages:function(){return v},getZoomedImage:function(){return E.original}};return L}});

I haven’t had the chance to figure out how to correct it myself yet. I imagine I’ll have to find a way to get that JS to talk to Ghost and pull the original image when zoomed in rather than using the optimized thumbnail that Ghost loads for the Gallery.

Sorry, I completely missed the link in your first post!

The script is not loading a thumbnail so that’s not the problem. It seems to be something to do with the way the script does it’s zoom-in transformation, it looks like it might be simply transforming the existing img element which on iOS in portrait mode doesn’t perform a re-draw for some reason :thinking:

Easiest solution could be swapping the script for another one that does a similar job.

1 Like

@VickyTheDemon Zoom.js is an alternative that I’ve seen many Ghost themes use.

Thanks @Stromfeldt, that looks promising. I’ll play with it some later.

Yeah it actually looks promising…Thank you so much.