Webäžã§ã®ç«¶äºãæ¿åããäžãããžãã¹ãŠã§ããµã€ãã®SEOãšãŠãŒã¶ãŒäœéšåäžã¯æ¬ ãããªãèŠçŽ ãšãªããŸãããããã§ã¯ããã®éèŠãªåœ¹å²ãæ ããç»åã®æé©åãã«ã¹ããããåœãŠããã®åºç€ããå ·äœçãªææ³ãããã«ã¯ããŒãžé床ãšãŠãŒã¶ãŒäœéšãæ¹åããããã®ã¢ããã€ã¹ãŸã§ãç¶²çŸ çã«ã玹ä»ããŸããç»åæé©åããSEOã®èŠ³ç¹ããã©ãã»ã©éèŠã§ããããé©åãªãã¡ã€ã«åœ¢åŒã®éžæãç»åã®å§çž®æ¹æ³ãªã©ãéããŠãããžãã¹ããŒãœã³ã®çæ§ãããå¹æçãªãŠã§ããµã€ãéå¶ãè¡ããããã«æåããŸããæãããå£èª¿ã§ãç»åæé©åã®åºæ¬ãããã®å®è·µäŸãŸã§ãä»ããã«ã§ã圹ç«ã€æ å ±ã玹ä»ããŠãããŸãã
ç»åæé©åã®åºæ¬ãšã¯
ç»åæé©åã®éèŠæ§
ãŠã§ãããŒãžã®ããŒãã£ã³ã°é床ã¯ãŠãŒã¶ãŒäœéšãæ€çŽ¢ãšã³ãžã³ã©ã³ãã³ã°ã®éèŠãªèŠçŽ ã§ããé©åãªç»åæé©åã¯ãŠã§ãããŒãžã®ããŒãæéãççž®ãããŠãŒã¶ãŒã®æ»åšæéã延ã°ãããšãã§ããŸãããã®ãããç»åã¯èŠæ ãã ãã§ãªããããã©ãŒãã³ã¹ã«ã圱é¿ãäžããéèŠãªèŠçŽ ã§ããããšãåãããŸãã
ããã«ãé©åã«æé©åãããç»åã¯ããŒã¿äœ¿çšéãåæžããç¹ã«ã¢ãã€ã«ããã€ã¹ã§ã®é²èŠ§æ§ãåäžãããŸããé床ãåäžãããšãããŒãžã®é¢è±çãäœäžããçµæãšããŠã³ã³ããŒãžã§ã³çã®åäžã«ã€ãªãããŸãã
å ããŠãç»åãæé©åããããšã¯ããŠã§ããµã€ãã®ã¢ã¯ã»ã·ããªãã£ãåäžãããããšã«ãç¹ãããŸããç»åã®altããã¹ããé©åã«èšå®ããããšã§ãèŠèŠé害ãæã€ãŠãŒã¶ãŒã«ãã³ã³ãã³ããäŒããããšãã§ããŸãã
ç»åæé©åãSEOã«äžãã圱é¿
ç»åæé©åã¯ãSEOã®èŠ³ç¹ããã極ããŠéèŠã§ããæ€çŽ¢ãšã³ãžã³ã¯ããŒãã£ã³ã°é床ãã©ã³ãã³ã°ã®éèŠãªææšãšããŠäœ¿çšããŠãããé©åã«æé©åãããç»åã¯ãã®é床ãåäžãããããšãã§ããŸãããŸããç»åã«é©åãªãã¡ã€ã«åãaltããã¹ããèšå®ããããšã¯ãæ€çŽ¢ãšã³ãžã³ãã³ã³ãã³ããç解ãããããããããSEOã«çŽæ¥åœ±é¿ãäžããŸãã
ç»åã§æ€çŽ¢ãããæã«è¡šç€ºããããç»åæ€çŽ¢çµæãã«ãããŠããæé©åãããç»åã¯é«ãäœçœ®ã«è¡šç€ºãããåŸåã«ãããŸããããã¯ãæ€çŽ¢ãšã³ãžã³ãç»åã®é¢é£æ§ãšå質ãè©äŸ¡ãããããæé©åãããç»åãåªå ãããããã§ãã
ããã«ãç»åã®ãµã€ãºãšãã©ãŒããããé©åã«æé©åãããŠãããšãããŒãžã®ããŒãæéãççž®ããããŠãŒã¶ãŒãšã¯ã¹ããªãšã³ã¹ãåäžããŸããããã¯ãæ€çŽ¢ãšã³ãžã³ãé«ãè©äŸ¡ãããã€ã³ãã§ãããå šäœçãªSEOæŠç¥ã«ãããŠéèŠã§ãã
ç»åãã¡ã€ã«åœ¢åŒã®éžæ
ç»åæé©åã«ãããŠãã¡ã€ã«åœ¢åŒã®éžæã¯ããã¡ã€ã«ãµã€ãºãšå質ã®ãã©ã³ã¹ãèããäžã§éèŠãªèŠçŽ ã§ããçŸåšäž»æµãšãªã£ãŠããç»åãã©ãŒãããã«ã¯ãJPEGãPNGãGIFãWebPãªã©ããããŸãã
JPEGã¯è²ã®å€ãåçãè€éãªç»åã«é©ããŠããããã¡ã€ã«ãµã€ãºãå°ããããªãããå質ãä¿æããããšãã§ããŸããPNGã¯éææ§ãä¿ã€å¿ èŠãããç»åãã现ãããã£ããŒã«ãéèŠããç»åã«é©ããŠããŸããGIFã¯ã¢ãã¡ãŒã·ã§ã³ãå«ãç»åã«äœ¿çšãããŸãããè²æ°ãéãããŠããããå質ãäœäžããããã§ãã
æè¿ãWebPãã©ãŒãããã泚ç®ãããŠããŸããWebPã¯ãJPEGããã25%å°ãããµã€ãºã§åçã®å質ãä¿æã§ãããããããã©ãŒãã³ã¹ãç¶æããªããããŒãæéãççž®ããã®ã«æå¹ã§ããå€ãã®ãã©ãŠã¶ã§ãµããŒããããŠãããããé©åãªæ¡ä»¶äžã§ã¯WebPã®æ¡çšãæ€èšãã䟡å€ããããŸãã
解å床ãšå§çž®ã®ãã©ã³ã¹
ç»åã®æé©åã§ã¯è§£å床ãšå§çž®ã®ãã©ã³ã¹ãéèŠã§ããé«è§£å床ã®ç»åã¯å質ãè¯ãã§ããããã¡ã€ã«ãµã€ãºã倧ãããªãããããŒãžã®ããŒãæéã«åœ±é¿ããŸããéã«ãé床ã«å§çž®ãããç»åã¯ãã¡ã€ã«ãµã€ãºã¯å°ãããªããŸãããå質ãäœäžããŠããŸããŸãã
äžè¬çã«ããŠã§ãçšã®ç»åã¯72dpiïœ96dpiã®è§£å床ã§ååãªå Žåãå€ãã§ãããã®è§£å床ç¯å²å ã§ãç»åã®ç®çã«å¿ããæé©ãªå§çž®ã¬ãã«ãèŠã€ããããšãéèŠã§ããå質ãä¿ã¡ãªãããã¡ã€ã«ãµã€ãºãæžããããšã§ããŠã§ãããŒãžã®ããã©ãŒãã³ã¹ãåäžããŸãã
ãŸããå§çž®ã®ããã»ã¹ã§ã¯ãç»åã®éèŠãªéšåã倱ãããªãããã«æ³šæããå¿ èŠããããŸããå§çž®ããŒã«ããã©ã°ã€ã³ã䜿çšããéã¯ããã®ãã©ã³ã¹ã調æŽã§ãããã®ãéžã¶ãšè¯ãã§ããããç»åã®å質ãšæ§èœã®ãã©ã³ã¹ãé©åã«ç®¡çããããšããæçµçã«ãŠãŒã¶ãŒãšã¯ã¹ããªãšã³ã¹ãšSEOã®äž¡æ¹ãåäžãããéµã§ãã
ç»åæé©åã®å ·äœçææ³
ç»åæé©åã®å ·äœçææ³
é©åãªãã¡ã€ã«åã®ä»ãæ¹
ç»åã®ãã¡ã€ã«åã¯SEOãšãŠãŒã¶ãŒäœéšåæ¹ã«åœ±é¿ãåãŒããŸããé©åãªãã¡ã€ã«åã䜿çšããããšã§ãæ€çŽ¢ãšã³ãžã³ãç»åã®å 容ãç解ãããããªãããã®çµææ€çŽ¢çµæã§ã®ã©ã³ãã³ã°ãåäžããŸãããã¡ã€ã«åã«ã¯ã察象ãšãªãããŒã¯ãŒããå«ãã€ã€ããé床ã«é·ããªããªããã泚æãå¿ èŠã§ãã
å ·äœçã«ã¯ããblue-summer-shirt.jpgãã®ããã«ããã€ãã³ã䜿ã£ãŠåèªãåºåããç»åãäœã§ããããæ確ã«ç€ºãååãä»ãããšè¯ãã§ããããåçŽãªãimg1.jpgãã®ãããªåœåã¯é¿ããå 容ãç解ããããååãå¿ãããŸãããã
ãŸãããã¡ã€ã«åã«ã¯ãããŒãžã®ããŒã¯ãŒããé©å®å«ããããšã§ããã®ç»åãããŒãžã®ã³ã³ãã³ããšã©ã®ããã«é¢é£ããŠãããã瀺ããŸããããã«ãããç»åæ€çŽ¢ã ãã§ãªããããŒãžå šäœã®æ€çŽ¢ãšã³ãžã³æé©åã«ãè²¢ç®ããŸãã
ALTå±æ§ã®éèŠæ§ãšæé©å
ALTå±æ§ã¯ãç»åãäœãè¡šããŠããããããã¹ã圢åŒã§èª¬æããå±æ§ã§ãããç»åã衚瀺ãããªããšããèŠèŠé害ãæã€ãŠãŒã¶ãŒãç»é¢èªã¿åããœããã䜿çšããŠããå Žåã«ç¹ã«éèŠã§ãããã®å±æ§ãé©åã«èšå®ããããšã§ãæ€çŽ¢ãšã³ãžã³ã«ç»åã®å 容ãäŒããSEOã«å¯äžããŸãã
ALTå±æ§ã®ããã¹ãã«ã¯ãç»åã«é¢é£ããäž»èŠããŒã¯ãŒããå«ããããšãæãŸããã§ããããŠãŒã¶ãŒãæ å ±ãåŸããããããé床ã«ããŒã¯ãŒããè©°ã蟌ããããŒã¯ãŒãã¹ã¿ããã£ã³ã°ãã¯é¿ããã¹ãã§ãã代ããã«ãèªç¶ã§æå³ã®ãã説æãå¿ãããŸãããã
äŸãã°ã補åç»åã§ããã°ã2021幎ã¢ãã«ã®éãå€çšã·ã£ããã®ããã«å ·äœçãªèª¬æãæå¹ã§ãããã®ããã«ããŠALTå±æ§ãå å®ãããããšã§ãæ€çŽ¢ãšã³ãžã³ã«ç»åã®è©³çŽ°ãäŒããæ€çŽ¢çµæã®åäžã«ç¹ãããŸãã
ç»åã®å§çž®æ¹æ³
é«ç»è³ªã®ç»åã¯èŠæ ããè¯ãåé¢ãããŒãžã®èªã¿èŸŒã¿æéãé ãããäž»èŠå ãšãªãåŸãŸãããŠãŒã¶ãŒäœéšãèãããšãããŒãžã®ããŒãé床ãæ¹åããããã«ç»åã®ãã¡ã€ã«ãµã€ãºãæé©åããããšãéèŠã§ããç»åã®å§çž®ãè¡ãããšã§ããã¡ã€ã«ãµã€ãºãæžãããªããããå質ãç¶æããããšãã§ããŸãã
ç»åã®å§çž®ã«ã¯ãæ§ã ãªããŒã«ããªã³ã©ã€ã³ãµãŒãã¹ãååšããŸãããããã®ããŒã«ã䜿çšããããšã§ãå¯èŠçãªå質ã®äœäžãæå°éã«æãã€ã€ããã¡ã€ã«ãµã€ãºãå¹ççã«å°ããããããšãã§ããŸããJPEG圢åŒã®ç»åã§ã¯ãå質ã60-80%çšåºŠã«èšå®ããããšãäžè¬çã§ãã
ãŸããWEBPãAVIFãšãã£ãææ°ã®ç»åãã©ãŒããããå©çšããããšãäžã€ã®æ段ã§ãããããã®ãã©ãŒãããã¯ãåŸæ¥ã®JPEGãPNGã«æ¯ã¹ãŠãã¡ã€ã«ãµã€ãºãå°ãããå質ãé«ããšããã¡ãªããããããŸãããã©ãŠã¶ã®äºææ§ã«æ³šæãã€ã€ã䜿çšãæ€èšãããšè¯ãã§ãããã
ã¬ã¹ãã³ã·ãç»åã®èšå®
ç°ãªãããã€ã¹ã§ã®èŠèŽãèæ
®ããã¬ã¹ãã³ã·ããªç»åã®èšå®ã¯ããŠãŒã¶ãŒäœéšã倧å¹
ã«åäžãããããšãã§ããŸããããã¯ãããã€ã¹ã®ç»é¢ãµã€ãºã解å床ã«å¿ããŠæé©ãªç»åãæäŸããæè¡ã§ããHTML5ã§ã¯ã<picture>
èŠçŽ ãsrcset
å±æ§ã䜿çšããããšã§ããããå®çŸããããšãã§ããŸãã
äŸãã°ãsrcset
å±æ§ã§ã¯ç»åã®ç°ãªãããŒãžã§ã³ãæå®ãããã©ãŠã¶ãèªåçã«ãŠãŒã¶ãŒã®ããã€ã¹ã«æé©ãªãã®ãéžæããŠè¡šç€ºããŸããç»åãè€æ°æºåããæéã¯ããããŸãããããã«ããã©ã®ããã€ã¹ããã¢ã¯ã»ã¹ããŠãæé©ãªç»åãæäŸã§ããããŒãžã®ããã©ãŒãã³ã¹æ¹åã«ç¹ãããŸãã
ã¬ã¹ãã³ã·ãç»åã®èšå®ã¯ãç¹ã«ã¢ãã€ã«ãã¡ãŒã¹ãã®èŠ³ç¹ããéèŠã§ããé©åãªãµã€ãºã®ç»åãæäŸããããšã§ãããŒã¿éãç¯çŽããããŒãã£ã³ã°ã¿ã€ã ãççž®ããããšãå¯èœã«ãªããŸããããã«ãã£ãŠããŠãŒã¶ãŒäœéšã®åäžã ãã§ãªããSEOã«ãããŠãæå©ã«åããŸãã
ããŒãžé床ãæ¹åããããã®ç»åæé©å
ãŠã§ããµã€ãã®ããã©ãŒãã³ã¹ãåäžãããéèŠãªã¹ãããã®äžã€ããç»åæé©åã§ããé©åãªææ³ãçšããããšã§ãããŒãžã®èªã¿èŸŒã¿é床ãå€§å¹ ã«æ¹åããçµæçã«SEOãšãŠãŒã¶ãŒäœéšã®äž¡æ¹ã«å¥œåœ±é¿ãããããããšãã§ããŸãã
ç»åã®é 延èªã¿èŸŒã¿
ç»åã®é 延èªã¿èŸŒã¿ã¯ããŠãŒã¶ãŒãã¹ã¯ããŒã«ããŠåããŠç»åã衚瀺ãããæ¹åŒã§ããããã«ãããåæã®ããŒãžèªã¿èŸŒã¿æéãççž®ãããããŒãžé床ãæ¹åãããŸãã
é
延èªã¿èŸŒã¿ãå®è£
ããæ¹æ³ã¯è€æ°ãããŸãããJavaScriptãç¹å®ã®ãã¬ãŒã ã¯ãŒã¯ã䜿çšããã®ãäžè¬çã§ãããŸããloading="lazy"
å±æ§ãç»åã¿ã°ã«è¿œå ããã ãã§ããã©ãŠã¶ãã€ãã£ãã®é
延èªã¿èŸŒã¿ãå©çšã§ããããã«ãªããŸããã
ãã®æè¡ãé©çšããããšã§ãç¹ã«ã³ã³ãã³ããè±å¯ãªããŒãžã§ã¯ããŒãžã®èªã¿èŸŒã¿é床ãåçã«åäžããŸãã
ç»åãµã€ãºã®èªå調æŽ
ãŠãŒã¶ãŒã䜿çšããŠããããã€ã¹ã«å¿ããŠç»åãµã€ãºãèªå調æŽããããšããéåžžã«å¹æçãªæé©åææ³ã§ããç°ãªãç»é¢ãµã€ãºã§æé©ãªç»åã衚瀺ããããšã§ãèªã¿èŸŒã¿æéãççž®ãã€ã€ããŠãŒã¶ãŒäœéšãåäžãããããšãå¯èœã§ãã
ãã®ãããªèªå調æŽã¯ãã¬ã¹ãã³ã·ããã¶ã€ã³ã®å®è£
ããsrcset
å±æ§ãå©çšããããšã§å®çŸã§ããŸããããã«ããããã©ãŠã¶ã¯ãŠãŒã¶ãŒã®ç»é¢ãµã€ãºã«åãããæé©ãªç»åãéžæããŠè¡šç€ºããããšãã§ããŸãã
ç»åãµã€ãºã®èªå調æŽã¯ãç¹ã«ã¢ãã€ã«ãŠãŒã¶ãŒã®èªã¿èŸŒã¿é床ã«å€§ããªåœ±é¿ãäžããŸãã
ãã£ãã·ã¥èšå®ã®å©çš
ç»åãã¡ã€ã«ããã£ãã·ã¥ã«ä¿åããããšã§ãäºåç®ä»¥éã®ããŒãžèšªåæã«èªã¿èŸŒã¿é床ãåäžãããããšãã§ããŸããããã¯ãåãç»åãäœåºŠããµãŒããŒããããŠã³ããŒãããå¿ èŠããªããªãããã§ãã
ãã©ãŠã¶ããµãŒããŒã®ãã£ãã·ã¥èšå®ãé©åã«è¡ãããšã§ããã®æé©åãè¡ãããšãå¯èœã§ãããã£ãã·ã¥ã®æå¹æéãé©åã«èšå®ããããšãéèŠã§ãéåžžãç»åãã¡ã€ã«ã«ã¯ä»ã®ã³ã³ãã³ããããé·ãæéèšå®ãããŸãã
ãã£ãã·ã¥ã掻çšããããšã§ãããŒãžã®èªã¿èŸŒã¿é床ãå¹æçã«æ¹åãããŠãŒã¶ãŒäœéšãåäžãããããšãã§ããŸãã
CDNã®æŽ»çš
ã³ã³ãã³ãé ä¿¡ãããã¯ãŒã¯ïŒCDNïŒã䜿çšããããšã«ãã£ãŠãç»åã®èªã¿èŸŒã¿é床ãå€§å¹ ã«åäžãããããšãã§ããŸããCDNã¯äžçäžã«ããŒã¿ã»ã³ã¿ãŒãæã¡ããŠãŒã¶ãŒã«æãè¿ããµãŒããŒããã³ã³ãã³ããé ä¿¡ããããšã§ãèªã¿èŸŒã¿æéãççž®ããŸãã
CDNãå©çšããããšã§ãç¹ã«å°ççãªè·é¢ãåå ã§çºçããé 延ã軜æžããã°ããŒãã«ãªèŠç¹ã§ãŠã§ããµã€ãã®ããã©ãŒãã³ã¹ãåäžãããããšãå¯èœã«ãªããŸãã
ãããã®æé©åææ³ã¯çžäºã«è£å®çã§ãããçµã¿åãããããšã§æè¯ã®çµæãåŸãããšãã§ããŸããããŒãžé床ã®æ¹åã¯SEOã©ã³ãã³ã°ãé«ãããŠãŒã¶ãŒäœéšãåäžãããããã«ãéåžžã«å¹æçãªæŠç¥ã§ãã
ãŠãŒã¶ãŒäœéšãåäžãããç»åæé©å
ããžã¥ã¢ã«ã®å°è±¡ãé«ãã
ãŠã§ããµã€ãã«ãããŠãããžã¥ã¢ã«èŠçŽ ã¯èšªåè ã®æ³šæãåŒããã¡ãã»ãŒãžãäŒããäžã§éåžžã«éèŠãªåœ¹å²ãæãããŸããç»åã®æé©åã¯ããããã®ç»åãé«å質ã§é®®æã§ããããšãä¿èšŒããããã«ãã£ãŠããžã¥ã¢ã«ã®å°è±¡ã倧ããåäžãããããšãã§ããŸãã
æé©åãããç»åã¯ãè²åœ©ã®è±ããã现éšã®é®®æããä¿ãããããããŠã§ããµã€ãã®å šäœçãªãã¶ã€ã³ãããé åçã«èŠããããšãã§ããŸããæããçãçããšããç»åã¯èšªåè ã®æ°åãé«ãããµã€ãã«é·ãçãŸãããä¿ããŸãã
ããã«ãé©åã«æé©åãããç»åã¯ããã©ã³ãã®ãããã§ãã·ã§ããªãºã ãšä¿¡é Œæ§ã蚪åè ã«äŒããããšãã§ããŸããé®®æãªç»åã¯ãäŒæ¥åã¯ãŠã§ããµã€ãã質ã«ãã ããã现éšãŸã§æ³šæãæã£ãŠããããšã瀺ãäžã€ã®ææšãšãªãåŸãŸãã
èªã¿èŸŒã¿é床ã®åäžã«ããå©ç¹
ç»åã®æé©åã¯ããŠã§ãããŒãžã®èªã¿èŸŒã¿é床åäžã«ã倧ããå¯äžããŸããç»åãã¡ã€ã«ã倧ãããšãããŒãžã®èªã¿èŸŒã¿æéãé·ããªããçµæãšããŠèšªåè ã®é¢è±çãé«ãŸããŸããããããæé©åã«ãããã¡ã€ã«ãµã€ãºãåæžããããšã§ããã®åé¡ãå¹æçã«è§£æ±ºããããšãã§ããŸãã
é«éåããããŠã§ãããŒãžã¯ãæ€çŽ¢ãšã³ãžã³ã«ããè©äŸ¡ãé«ããªããæ€çŽ¢çµæã®äžäœã«è¡šç€ºãããå¯èœæ§ãé«ãŸããŸããããã¯ãæ€çŽ¢ãšã³ãžã³ã蚪åè ã«è¯å¥œãªäœéšãæäŸãããŠã§ããµã€ãã奜ãããã§ãããããã£ãŠãç»åãæé©åããããšã¯ãSEOæŠç¥ã«ãããŠãéèŠãªåœ¹å²ãæãããŸãã
èªã¿èŸŒã¿é床ã®åäžã¯ãã¢ãã€ã«ãŠãŒã¶ãŒã«ãšã£ãŠã倧ããªå©ç¹ãšãªããŸããã¢ãã€ã«ããã€ã¹ã¯ãã¹ã¯ãããã³ã³ãã¥ãŒã¿ãããåŠçèœåãéãããŠãããããæé©åãããç»åãå¿«é©ãªé²èŠ§äœéšãæäŸããŸãã
ã¢ãã€ã«ãã¡ãŒã¹ãã®èŠç¹
ãŠã§ããã©ãã£ãã¯ã®å€§éšåãã¢ãã€ã«ããã€ã¹ããæ¥ãŠããçŸåšãã¢ãã€ã«ãã¡ãŒã¹ãã®ã¢ãããŒãã¯å¿ é ãšãªã£ãŠããŸããç»åãæé©åããéã«ã¯ãã¢ãã€ã«ãŠãŒã¶ãŒãå¿«é©ã«é²èŠ§ã§ããããã«ç¹å¥ãªé æ ®ãå¿ èŠã§ãã
ã¬ã¹ãã³ã·ããã¶ã€ã³ã¯ãããã€ã¹ã®ç»é¢ãµã€ãºã«å¿ããŠç»åãµã€ãºãèªå調æŽããããšã§ãã¢ãã€ã«ãŠãŒã¶ãŒã«é©ããäœéšãæäŸããŸããç»åãæé©åããããšã§ããããã®ç»åãã¢ãã€ã«ããã€ã¹äžã§è¿ éã«èªã¿èŸŒãŸãããŠãŒã¶ãŒäœéšãåäžããŸãã
ç»åã®ãã©ãŒãããéžæã«ãããŠããã¢ãã€ã«ãã¡ãŒã¹ããèæ ®ããããšãéèŠã§ããäŸãã°ãWebPãã©ãŒãããã¯åŸæ¥ã®JPEGãPNGã«æ¯ã¹ãŠãã¡ã€ã«ãµã€ãºãå€§å¹ ã«åæžã§ããã¢ãã€ã«ããã€ã¹ã®èªã¿èŸŒã¿æéãççž®ããŸãã
ã¢ã¯ã»ã·ããªãã£ã®èæ ®
ç»åã®æé©åãè¡ãéã«ã¯ããŠã§ãã¢ã¯ã»ã·ããªãã£ã®èŠ³ç¹ãããé æ ®ãå¿ èŠã§ããèŠèŠé害ãæã€ãŠãŒã¶ãŒããŠã§ãã³ã³ãã³ããç解ã§ããããã«ãç»åã«ä»£æ¿ããã¹ãïŒaltå±æ§ïŒãæäŸããããšãéèŠã§ãã
代æ¿ããã¹ãã¯ãç»åãäœãè¡šããŠããããç°¡æœã«èª¬æãããã®ã§ãããç»é¢èªã¿åããœãããŠã§ã¢ã䜿çšãããŠãŒã¶ãŒã«ç»åã®å 容ãäŒããŸãããã®ããã«ãç»åã®æé©åã«ã¯æè¡çãªåŽé¢ã ãã§ã¯ãªãããŠã§ããµã€ãã蚪ããå šãŠã®ãŠãŒã¶ãŒã«å¯Ÿããé æ ®ãå«ãŸããŸãã
ããã«ãè²èŠç°åžžã®ãŠãŒã¶ãŒãèæ ®ããŠç»åãéžã¶ããšããã¢ã¯ã»ã·ããªãã£åäžã«å¯äžããŸããè²ãèå¥ããã®ãå°é£ãªãŠãŒã¶ãŒã§ãæ å ±ãåãåããããã«ãè²ã ãã§ãªã圢ããã¿ãŒã³ãå©çšããŠæ å ±ãäŒããã¹ãã§ãã
ç»åæé©åããŒã«ãšå©çšæ¹æ³
ç»åæé©åããŒã«ãšå©çšæ¹æ³
ãªã³ã©ã€ã³ç»åå§çž®ããŒã«
ãŠã§ãäžã§å©çšã§ããç»åå§çž®ããŒã«ã¯ãç»åã®æé©åããã»ã¹ã容æãã€è¿ éã«ããããŒã«ã§ãããããã®ããŒã«ã§ã¯ãJPEGãPNGãSVGãªã©ãå€å²ã«ããããã©ãŒãããã®ãã¡ã€ã«ããµããŒãããŠãããé«å質ãªç»åå§çž®ãæäŸããŸãã
å ·äœäŸãšããŠãTinyPNGãCompressor.ioãªã©ã人æ°ããããç¹ã«TinyPNGã¯ãéæ床ãä¿ã£ããŸãŸPNGç»åãå¹çè¯ãå§çž®ããæ©èœã§ç¥ãããŠããŸãããŠãŒã¶ãŒã¯ããã©ãã°ã¢ã³ãããããã®åçŽãªæäœã ãã§ãæ°ç§å ã«ç»åãã¡ã€ã«ã®ãµã€ãºãæžããããšãå¯èœã§ãã
ãªã³ã©ã€ã³ããŒã«ã®å©çšã¯ããœãããŠã§ã¢ã®ã€ã³ã¹ããŒã«ãäžèŠã§ããç¹ãããã€ã§ãã©ãã§ãã¢ã¯ã»ã¹ã§ããå©äŸ¿æ§ãç¹é·ã§ãããããã®ããŒã«ã䜿ã£ãŠãå¹æçã«ç»åãµã€ãºãåæžãããŠã§ãããŒãžã®ããŒãæéãæ¹åããŸãããã
ç»åç·šéãœãããŠã§ã¢ã®æŽ»çš
Adobe PhotoshopãGIMPã®ãããªç»åç·šéãœãããŠã§ã¢ã¯ãç»åã®æé©åã«ãããŠæŽãªãèªç±åºŠãšå¶åŸ¡ãæäŸããŸãããããã®ãœãããŠã§ã¢ã§ã¯ããªãµã€ãºãã¯ãããã³ã°ãå§çž®ã¬ãã«ã®èª¿æŽãç»åã®å質ãç¶æããªããå¹æçã«ãã¡ã€ã«ãµã€ãºãåæžã§ããå€åœ©ãªæ©èœãæã£ãŠããŸãã
ãŸããç»åã®è²æ°ãæžããããšã§ãã¡ã€ã«ãµã€ãºãåæžãããã€ã³ããã¯ã¹ã«ã©ãŒãæ©èœããWebçšã«ä¿åããéã«ç»åãæé©åããæ©èœãåãã£ãŠããããããŠã§ãããŒãžãžã®è² è·ãæãã€ã€ããããžã¥ã¢ã«ã®è³ªãä¿ã€ããšãã§ããŸãã
ãœãããŠã§ã¢ãå©çšããããšã§ãå°éçãªç¥èããããŠãŒã¶ãŒã¯ãç®çãšãããã©ãããã©ãŒã ãããã€ã¹ã«æé©åãããç»åãäœæããããšãå¯èœã§ããããã¯ãããŒãžã®èªã¿èŸŒã¿é床ãSEOããã©ãŒãã³ã¹ã«ãçŽæ¥çãªåœ±é¿ãäžããŸãã
WordPressãã©ã°ã€ã³ã«ããèªåæé©å
WordPressãµã€ããéå¶ããŠããå Žåãç»åæé©åãèªååãããã©ã°ã€ã³ãéåžžã«äŸ¿å©ã§ãã人æ°ã®ãããã©ã°ã€ã³ã«ã¯ãWP SmushãEWWW Image OptimizerãShortPixel Image Optimizerãªã©ããããŸãã
ãããã®ãã©ã°ã€ã³ã¯ãç»åãã¢ããããŒãããéã«èªåçã«æé©åãè¡ãããããŠã§ããµã€ãã®éå¶è ãã³ã³ãã³ãã¯ãªãšã€ã¿ãŒã«ãšã£ãŠãæéã®ããããªãå¹æçãªãœãªã¥ãŒã·ã§ã³ãšãªããŸããå§çž®çã®èšå®ãç¹å®ã®ãã¡ã€ã«ã¿ã€ãã®é€å€ãªã©ãèªç±åºŠã®é«ãã«ã¹ã¿ãã€ãºãå¯èœã§ãã
ããã«ããããã®ãã©ã°ã€ã³ã䜿çšããããšã§ããµã€ãå šäœã®ç»åãäžæ¬ã§æé©åããæ©èœããããæéã®ç¯çŽã«ãã€ãªãããŸãããŠã§ããµã€ãã®ããã©ãŒãã³ã¹ãšãŠãŒã¶ãŒäœéšã®åäžã«å€§ããè²¢ç®ããã§ãããã
ããããããŒããŒã«ã®å©çš
Webéçºè ã«ãšã£ãŠããã©ãŠã¶ã®ããããããŒããŒã«ã¯ç»åæé©åããã»ã¹ã®åŒ·åãªè£å©ãšãªããŸããGoogle ChromeãFirefoxãšãã£ãäž»èŠãªãã©ãŠã¶ã¯ãç»åãã¡ã€ã«ããŠã§ãããŒãžã«äžãã圱é¿ãåæããæé©åã®ããã®æšå¥šäºé ãæäŸããæ©èœãåããŠããŸãã
äŸãã°ãChromeã®ãLighthouseãããŒã«ã䜿ãããšã§ãç»åã®æé©åã®æ©äŒãç¹å®ããå ·äœçãªææ¡ãåŸãããšãå¯èœã§ããããã«ã¯ãé©åãªç»åãã©ãŒãããã®éžæããã¬ã¹ãã³ã·ãã€ã¡ãŒãžã®äœ¿çšãé 延èªã¿èŸŒã¿ã®å®è£ ãªã©ãå«ãŸããŸãã
ããããããŒããŒã«ã掻çšããããšã§ãããã©ãŒãã³ã¹ã®åé¡ãå ·äœçã«ç¹å®ããããã«å¿ããæé©åææ³ãé©çšããããšãã§ããŸããããã¯ãSEOåäžã®ããã ãã§ãªãããŠãŒã¶ãŒäœéšã®æ¹åã«ãçŽçµããéèŠãªã¹ãããã§ãã
ç»åæé©åã®å®è·µäŸãšæŠç¥
æåäºäŸã®åæ
ç»åæé©åã«ãããæåã®äŸã¯ããŠã§ããµã€ãã®ããŒãã£ã³ã°æéã®ççž®ããGoogleã®ç»åæ€çŽ¢ã§ã®äžäœè¡šç€ºãªã©ãæ§ã ãªåœ¢ã§çŸããŸããããããæåäºäŸãåæããããšã§ãã©ã®ãããªç»åãã©ãŒããããå§çž®ææ³ãå¹æçã§ãããåŠã¶ããšãã§ããŸãã
ãŸããALTããã¹ããã¿ã€ãã«ã®é©åãªäœ¿çšã¯ãSEO察çãšããŠãéèŠã§ãããããã®å°ããªå·¥å€«ããæ€çŽ¢çµæã§ã®è¡šç€ºåäžã«çŽçµããŸããå®éã®äºäŸã§ã¯ãããŒã¯ãŒããå«ãå ·äœçãªALTããã¹ãã®å°å ¥ã«ããããã©ãã£ãã¯ãå€§å¹ ã«åäžããäŸããããŸãã
å ããŠãç»åã®ãµã€ãºãã¢ã¹ãã¯ãæ¯ãwebããŒãžã®ã¬ã€ã¢ãŠãã«åãããŠæé©åããããšã§ããŠãŒã¶ãŒäœéšãåäžããŸãããã®ããã«ãããã€ãã®æåäºäŸãåæããããšã§ãç»åæé©åã®éèŠãªãã€ã³ããææ¡ããããšãå¯èœã§ãã
ç»åæé©åã®èšç»ç«æ¡
ç»åæé©åãè¡ãéã¯ããŸãæé©ãªç»åãµã€ãºããã©ãŒããããéžå®ããããšããå§ããŸãããã®éžæã¯ããŠã§ããµã€ãã®ããŒãé床ããŠãŒã¶ããªãã£ã«çŽæ¥åœ±é¿ããããã泚ææ·±ãæ€èšãå¿ èŠã§ãã
次ã«ãå¹æçãªALTããã¹ããšãã£ãã·ã§ã³ã®äœæãèšç»ããŸããããã«ãããç»åãæ£ããã€ã³ããã¯ã¹ãããæ€çŽ¢çµæã«ãããŠæ£ç¢ºãªã³ã³ããã¹ãã§è¡šç€ºãããããã«ãªããŸãããŸãããã£ãã·ã§ã³ã¯ãŠãŒã¶ãŒãã³ã³ãã³ããç解ããäžã§åœ¹ç«ã¡ãŸãã
ããã«ãç»åã®å§çž®ã«é¢ããŠããç»è³ªãæãªããã«å¹æçã«ãã¡ã€ã«ãµã€ãºãåæžããæ¹æ³ãèšç»ã«å«ããããšãéèŠã§ããããã«ãããããŒãžã®ããŒãé床ãåäžãããããŸããé©åã«èšç»ãããç»åæé©åæŠç¥ã¯ããŠã§ããµã€ãã®ããã©ãŒãã³ã¹ã倧ããæ¹åãããããšãã§ããŸãã
å®æçãªç»åã®ã¬ãã¥ãŒãšæŽæ°
ç»åã®å 容ãSEOã®ãã¬ã³ãã¯åžžã«å€åãããããå®æçãªã¬ãã¥ãŒãšæŽæ°ãäžå¯æ¬ ã§ãããŠã§ããµã€ãã®ç»åãå®æçã«èŠçŽãããšã§ãå€ããªã£ãç»åãæé©åãäžååãªç»åãèŠã€ãåºããæŽæ°ããããšãã§ããŸãã
ãã®éçšã§ã¯ãæ°ããå§çž®æè¡ããã©ãŒããããå©çšå¯èœã«ãªã£ãŠããªããã確èªããŸããæã«ã¯ãå€ãç»åãããå¹ççãªãã©ãŒãããã«å€æããã ãã§ãããã©ãŒãã³ã¹ãåäžããããšããããŸãã
å ããŠãç»åã®ALTããã¹ãããã£ãã·ã§ã³ã«å¯ŸããŠããããŒã¯ãŒãã®ãã¬ã³ããæ€çŽ¢ååã«åºã¥ããŠãå®æçãªèŠçŽããè¡ãããšãéèŠã§ããããã«ãããSEO察çãšããŠã®å¹æãé«ãããŠã§ããµã€ããžã®ãã©ãã£ãã¯å¢å ã«ç¹ãããŸãã
ææ°ãã¬ã³ãã®é©çš
ç»åæé©åã®åéã§ã¯ãæ°ããªæè¡ããã¬ã³ãã絶ããç»å ŽããŸãããŠã§ãããŒãžã®ããã©ãŒãã³ã¹ãæ倧åããããã«ã¯ããããã®ææ°ãã¬ã³ãã«ææã§ããããšãéèŠã§ãã
äŸãã°ãWebPãAVIFãšãã£ãææ°ã®ç»åãã©ãŒãããã¯ãåŸæ¥ã®ãã©ãŒãããã«æ¯ã¹ãŠåªããå§çž®çãå®çŸããŸãããããã掻çšããããšã§ãç»åã®å質ãèœãšãããšãªããããé«éãªããŒãžããŒããéæã§ããŸãã
ãŸããã¬ã¹ãã³ã·ãç»åã®æè¡ã¯ãããã€ã¹ã®çš®é¡ã«å¿ããŠé©åãªãµã€ãºã®ç»åãæäŸããããšã§ãã¢ãã€ã«ãŠãŒã¶ãŒã®äœéšãå€§å¹ ã«åäžãããŸãããã®ããã«ãææ°ã®ãã¬ã³ããé©çšããããšã§ãSEOãšãŠãŒã¶ãŒäœéšã®äž¡æ¹ãå¹æçã«æ¹åããããšãã§ããŸãã
ãŸãšã
ç»åæé©åã¯SEOãšãŠãŒã¶ãŒäœéšãåçã«æ¹åããŸãããã®ããã»ã¹ã¯ãé©æ£ãªãã¡ã€ã«åã®äœ¿çšãALTå±æ§ã®å å®åãå¹ççãªå§çž®æè¡ã®å¿çšãªã©ãå«ã¿ãŸããç»åãã¡ã€ã«åœ¢åŒãé©åã«éžæãã解å床ãšå§çž®ã®ãã©ã³ã¹ãèŠæ¥µããããšãéèŠã§ãããŸããã¬ã¹ãã³ã·ãç»åã®èšå®ããããŒãžé床åäžã®ããã®é 延èªã¿èŸŒã¿ãCDNã®æŽ»çšã¯äžå¯æ¬ ã§ãããŠãŒã¶ãŒäœéšãé«ããããã«ã¯ãããžã¥ã¢ã«ã®è³ªãä¿ã¡ã€ã€èªã¿èŸŒã¿é床ãæ©ããããšãå¿ èŠã§ãããªã³ã©ã€ã³ããŒã«ãWordPressãã©ã°ã€ã³ãç»åç·šéãœãããŠã§ã¢ã掻çšããŠå¹æçã«ç»åãæé©åããå®æçãªã¬ãã¥ãŒãšææ°ãã¬ã³ãã®é©çšã§ãSEOã©ã³ãã³ã°ãšãŠãŒã¶ãŒæºè¶³åºŠãåäžãããŸããããããžãã¹ããŒãœã³ã®ã¿ãªãããç»åæé©åã§ãŠã§ãããŒãžã®ããã©ãŒãã³ã¹ãæ倧éã«åŒãåºããŸãããã